Why not use e702e6d5-195e-4bf0-934d-2197666c4a2f for 8.7 and 4a84c039-910b-4c7a-9f74-50452b765e9d for 9.1? It's what we always did AFAIK... GA images don't get removed they will just be renamed to something like $COMPOSE-updates-$DATE if the -latest-ga tag gets updated...
Let's follow up on this here https://coreos.slack.com/archives/C0235DZB0DT/p1669367312060539