in ubuntu-date:system-data/var/lib/snapd/snaps/ of the disk image, there's no core20_1550.snap.
$ tree img/system-data/var/lib/snapd/snaps/ img/system-data/var/lib/snapd/snaps/ ├── core20_1518.snap ├── pc_115.snap ├── pc-kernel_1032.snap └── snapd_16010.snap
in ubuntu- date:system- data/var/ lib/snapd/ snaps/ of the disk image, there's no core20_1550.snap.
$ tree img/system- data/var/ lib/snapd/ snaps/ data/var/ lib/snapd/ snaps/
img/system-
├── core20_1518.snap
├── pc_115.snap
├── pc-kernel_1032.snap
└── snapd_16010.snap