Hmm - odd,
Michal has checked the files and the build logs as he outlined above.
And in addition to all those checks being done, if we just grep for all final dependencies and compare there is no difference (other than a glibc min version level).

I know names are not too helpful:
- ~ppa1 = LTO-off
- ~ppa2 = LTO-on

This compares amd64 vs i386 without LTO enabled 

$ grep "Depends" buildlog_ubuntu-lunar-amd64.heimdal_7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2_BUILDING.txt  > amd64.deps
$ grep "Depends" buildlog_ubuntu-lunar-i386.heimdal_7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2_BUILDING.txt  > i386.deps
$ diff -Naur amd64.deps i386.deps
--- amd64.deps	2023-05-16 10:18:49.754334825 +0200
+++ i386.deps	2023-05-16 10:18:51.106344323 +0200
@@ -8,10 +8,10 @@
  Depends: debconf (>= 0.5.00) | debconf-2.0, heimdal-clients, krb5-config, lsb-base, openbsd-inetd | inet-superserver, libasn1-8-heimdal (>= 1.4.0+git20110226), libc6 (>= 2.34), libcap-ng0 (>= 0.7.9), libgssapi3-heimdal (>= 1.4.0+git20110226), libhcrypto5-heimdal (>= 1.4.0+git20110226), libhdb9-heimdal (>= 1.6~git20131117), libheimntlm0-heimdal (>= 1.4.0+git20110226), libkadm5srv8-heimdal (>= 7.8.git20221115.a6cf945+dfsg), libkdc2-heimdal (>= 1.4.0+git20110226), libkrb5-26-heimdal (>= 1.7~git20160418), libroken19-heimdal (>= 1.7~git20150920), libsl0-heimdal (>= 1.4.0+git20110226)
  Depends: comerr-dev, libasn1-8-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libgssapi3-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libhcrypto5-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libhdb9-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libheimbase1-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libhx509-5-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libkadm5clnt7-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libkadm5srv8-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libkafs0-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libkdc2-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libkrb5-26-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libwind0-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libotp0-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libsl0-heimdal (= 7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2), libc6 (>= 2.34), libcom-err2 (>= 1.43.9), libroken19-heimdal (>= 1.4.0+git20110226)
  Depends: krb5-config, openbsd-inetd | inet-superserver, libc6 (>= 2.34), libkrb5-26-heimdal (>= 1.4.0+git20110226), libroken19-heimdal (>= 1.4.0+git20110226)
- Depends: libc6 (>= 2.14), libcom-err2 (>= 1.43.9), libroken19-heimdal (>= 1.4.0+git20110226)
+ Depends: libc6 (>= 2.8), libcom-err2 (>= 1.43.9), libroken19-heimdal (>= 1.4.0+git20110226)
  Depends: libasn1-8-heimdal (>= 1.4.0+git20110226), libc6 (>= 2.34), libcom-err2 (>= 1.43.9), libhcrypto5-heimdal (>= 1.4.0+git20110226), libheimntlm0-heimdal (>= 1.4.0+git20110226), libkrb5-26-heimdal (>= 1.6~git20131117), libroken19-heimdal (>= 1.7~git20150920)
  Depends: libasn1-8-heimdal (>= 1.4.0+git20110226), libc6 (>= 2.36), libheimbase1-heimdal (>= 1.4.0+git20110226), libroken19-heimdal (>= 1.7~git20150920)
- Depends: libasn1-8-heimdal (>= 1.6~git20120311g), libc6 (>= 2.14), libcom-err2 (>= 1.43.9), libdb5.3, libkrb5-26-heimdal (>= 1.7~git20161112), libldap2 (>= 2.6.2), libroken19-heimdal (>= 1.7~git20150920), libsqlite3-0 (>= 3.5.9)
+ Depends: libasn1-8-heimdal (>= 1.6~git20120311g), libc6 (>= 2.8), libcom-err2 (>= 1.43.9), libdb5.3, libkrb5-26-heimdal (>= 1.7~git20161112), libldap2 (>= 2.6.2), libroken19-heimdal (>= 1.7~git20150920), libsqlite3-0 (>= 3.5.9)
  Depends: libc6 (>= 2.34)
  Depends: libc6 (>= 2.4), libhcrypto5-heimdal (>= 1.4.0+git20110226), libkrb5-26-heimdal (>= 1.4.0+git20110226), libroken19-heimdal (>= 1.7~git20150920), libwind0-heimdal (>= 1.4.0+git20110226)
  Depends: libasn1-8-heimdal (>= 1.4.0+git20110226), libc6 (>= 2.34), libcom-err2 (>= 1.43.9), libhcrypto5-heimdal (>= 1.4.0+git20110226), libheimbase1-heimdal (>= 1.6~git20131117), libroken19-heimdal (>= 1.7~git20150920), libwind0-heimdal (>= 1.4.0+git20110226)
@@ -23,4 +23,4 @@
  Depends: libc6 (>= 2.33), libdb5.3, libhcrypto5-heimdal (>= 1.4.0+git20110226)
  Depends: libc6 (>= 2.36), libcrypt1 (>= 1:4.1.0)
  Depends: libc6 (>= 2.11), libedit2 (>= 2.11-20080614-0)
- Depends: libc6 (>= 2.14), libcom-err2 (>= 1.43.9)
+ Depends: libc6 (>= 2.4), libcom-err2 (>= 1.43.9)



And checking the PPAs build if LTO was really back on I indeed see "... -ffat-lto-objects ..." used in
https://launchpadlibrarian.net/646899573/buildlog_ubuntu-lunar-amd64.heimdal_7.8.git20221117.28daf24+dfsg-1ubuntu1~ppa2_BUILDING.txt.gz