I'm not entirely convinced NetworkManager is working correctly this regard? I *was* checking the wifi regulatory domain with "iw reg get" which consistently shows UNSET both globally and for phy#0 under the desktop for Pi images:

$ iw reg get
global
country 00: DFS-UNSET
	(2402 - 2472 @ 40), (N/A, 20), (N/A)
	(2457 - 2482 @ 20), (N/A, 20), (N/A), AUTO-BW, PASSIVE-SCAN
	(2474 - 2494 @ 20), (N/A, 20), (N/A), NO-OFDM, PASSIVE-SCAN
	(5170 - 5250 @ 80), (N/A, 20), (N/A), AUTO-BW, PASSIVE-SCAN
	(5250 - 5330 @ 80), (N/A, 20), (0 ms), DFS, AUTO-BW, PASSIVE-SCAN
	(5490 - 5730 @ 160), (N/A, 20), (0 ms), DFS, PASSIVE-SCAN
	(5735 - 5835 @ 80), (N/A, 20), (N/A), PASSIVE-SCAN
	(57240 - 63720 @ 2160), (N/A, 0), (N/A)

phy#0
country 99: DFS-UNSET
	(2402 - 2482 @ 40), (6, 20), (N/A)
	(2474 - 2494 @ 20), (6, 20), (N/A)
	(5140 - 5360 @ 160), (6, 20), (N/A)
	(5460 - 5860 @ 160), (6, 20), (N/A)

Still, perhaps "iw" doesn't know about changes that wpa_supplicant makes? On a freshly flashed jammy pi desktop card, I get the following output when looking for REGDOM in the wpa_supplicant logs:

$ journalctl -u wpa_supplicant -g REGDOM
-- Boot 732bf3d726d543d4985f9e8ded5b5dc3 --
May 09 11:19:54 miss-piggy wpa_supplicant[727]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD

The "WORLD" region is presumably consistent with "UNSET" so it doesn't look like NetworkManager or wpa_supplicant is setting things correctly there. I wondered if perhaps it this only works on some APs? So here's the output from my regular development Pi. This also runs the jammy desktop, but it's not a freshly flashed image -- it's been upgraded thru every release since hirsute so it's probably a bit crufty -- but it has travelled with me to various places so it's seen a few different access points (it spends most of its time on ethernet at home though, so the lack of lots of REGDOM changes is not too surprising):

-- Boot 3342ed4b84f14e6a8f7b900d240b2c4d --
-- Boot d9087ec569c64e258d9b0a39d5d51c81 --
-- Boot b4c27a9655d747d48fc16329f73ad596 --
-- Boot d431767f6d89494bba39cc9ab9bce969 --
Sep 29 00:09:43 kermit wpa_supplicant[1081]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 345a7579a52147aea56af3152178c199 --
Sep 29 09:28:02 kermit wpa_supplicant[1077]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 624126fce6cc45abad47cb42b9ac256f --
-- Boot e424d65195804a6eae2f948ee1e4ef38 --
-- Boot 77fb125a0ecc4df985d5317cd536b54a --
-- Boot da38e67821874b3fa66a330acf17f18c --
-- Boot 02be9377913d4886b21988b903d1b4cd --
-- Boot 8a6dc8a10b0f42689056adacb374d269 --
-- Boot 85bbc4cfc473439a899e467a2debb201 --
-- Boot fa07d0686c68401696caf2b3e4c402dd --
Jan 14 15:09:22 kermit wpa_supplicant[87530]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 9e7e7bf75790439bbc2e72371a14c8ab --
-- Boot a70d0f3889794224a7bf370998aaf7dd --
-- Boot bd314e15c8f1415eb75c9950129edd5b --
-- Boot c54489d0e45b4318b1b07d88bdaff7ea --
-- Boot 370a4871b0ec43f9a1b58cab78ac875c --
-- Boot 4756c93714f247009f5b93f228925455 --
-- Boot 884e307c2a13455b9fbb913e0a0f0c29 --
-- Boot bad77d689f714ca88d38f498cd8bfa2b --
-- Boot 1cf2c96be69748afa60489603ef8b771 --
-- Boot 09375e4eaaf94141a8cfe904bc303989 --
-- Boot 8fa2bdfb2e6e4ad0abeda9b3a79ac37a --
-- Boot 6c23de48f7a748d995cce77b9a908d3f --
-- Boot 364f760176b54df5b3fcaa5b978f3e70 --
-- Boot ff656412414f4c7880079f7bbf07400a --
-- Boot ebb1115d58724cf9bd544028d01c6e96 --
-- Boot 5c85c03736934ed6a2426544f5f98b88 --
-- Boot 6051d9f10827419996db1bfa376ec562 --
-- Boot 4996ddb853a248268b27e93adff373e1 --
-- Boot 0b7927e93a38434683395e88d202a8e1 --
Feb 14 09:57:26 kermit wpa_supplicant[1030]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 08038d28c346496eb7884859c306ca4c --
-- Boot b2c62ed0866d4618ac058670dbaae672 --
Feb 17 01:37:49 kermit wpa_supplicant[1032]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 5a2883f8ce074e748e9a94beaf72f123 --
-- Boot ec2157fa46fa48a3ba3445bfa7fe4b1b --
-- Boot e2dbc92b2764473eb8d65a1f7e6df5df --
-- Boot ec2157fa46fa48a3ba3445bfa7fe4b1b --
-- Boot e2dbc92b2764473eb8d65a1f7e6df5df --
-- Boot a8ef52e6c63949cea168ea8c1d06d148 --
Feb 23 10:43:59 kermit wpa_supplicant[1027]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 319081b9562a4c20aa1560a4fe998f19 --
-- Boot 4d3841cc1dbb4906a4465dd2122f64a8 --
Feb 26 18:18:07 kermit wpa_supplicant[1048]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=USER type=COUNTRY alpha2=DE
-- Boot 8729c7f4e1ae45dcbece9aeceb9b19cb --
-- Boot 8034051089274a34ba65bc96d749a9b7 --
-- Boot 8729c7f4e1ae45dcbece9aeceb9b19cb --
Mar 03 10:07:39 kermit wpa_supplicant[1040]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 8034051089274a34ba65bc96d749a9b7 --
Mar 11 11:20:39 kermit wpa_supplicant[1040]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot dcd973755091479b9be508eaf11667dd --
-- Boot b0c3f4f9a2d64a8a959844ad1773e6c1 --
-- Boot e0fc49c4dc894233b0541b66700b5fb3 --
-- Boot 1f2be083fe2e42849d9e869c1fbcde92 --
-- Boot 76ecf6d5e894408dae933c7a598e1ae9 --
-- Boot 5fcfbff4b29f4f2ab527c36f61594d03 --
-- Boot 15f5817168b84c3b9a5dcfa0f23c5543 --
-- Boot 44d914f21c4444d582947dceb31f3afe --
-- Boot 238dbb8b62164482a60147f2a6282025 --
-- Boot 9c66088689b641cd9c414320f6996fb0 --
-- Boot d1cc9ac5cd304da8828bc78ff04d2281 --
Apr 01 11:31:13 kermit wpa_supplicant[1070]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 42f146dbf914494698554783a15c5f0c --
-- Boot 381cd6a085d34a969a12b0f70f494649 --
-- Boot 58ca2d99d67641a8b31b0df25ae37644 --
Apr 07 22:54:56 kermit wpa_supplicant[1086]: wlan0: CTRL-EVENT-REGDOM-CHANGE init=CORE type=WORLD
-- Boot 5a5eea05df5f43f292419c5c983cf14d --
-- Boot 136d1be22bf0465a8f275a3b921a1a38 --
-- Boot a054dd8d8fe7425cb8c3d28c27ef1786 --
-- Boot 8f7d36b281744f7f9753abe546db7cf9 --
-- Boot 890cf4c9b93540bc83440d7773416828 --
-- Boot f159c0c4c67b4468882374ce194da806 --
-- Boot 59124b1e8b87434ca38c4e3278367ea4 --
-- Boot cc7d8831649d4936a66f200b363890bd --
-- Boot 2e9a85dc69194973a1fd95a55537bec1 --
-- Boot cf0bca78a10f4d40b27e12f8930db7ed --
-- Boot 95e066d50b9a4f468eafcfcb4403bf0a --
-- Boot d6b96bc9d2da48bb9410dab66a35de2c --
-- Boot 6a1885e322674da689e6ab03812834d5 --
-- Boot 265f11639efe4f6888de3c26bbcb24ec --
-- Boot 5b96ffce43504e61ba66aca930e18c57 --
-- Boot f8ca9d9135d24950ba805e2a261fec17 --
-- Boot 866d560e03ec4262969b751ea7edcca1 --
-- Boot 1a517bf700c14e4c80c33303f42b9e1e --
-- Boot e85bdc80cb364b0195c7fec08597b4f2 --
-- Boot 65488c22c3c0439aa928aaabcfd87181 --
-- Boot c63d9371838e4c95beaa3a4c3d9c38c2 --
-- Boot 66e65c4fc40946eea75112666829870a --

So the upgraded image never sets "GB" either, but it did correctly figure out I'd dragged it into Germany (DE) for the engineering sprint in late February! Still, after that it was back to "WORLD" back in blighty.

Am I looking in the wrong place for REGDOM events? Is there another wpa_supplicant instance that's setting things correctly? Or perhaps there's some setting I'm missing? (although that sounds unlikely given it did correctly figure out Germany).