I have been on the same boat a while ago. Of course it was a deployment that caught on and was serving longer than expected.
I don't recall how many versions I skipped exactly (1-2 years worth of updates). Of course no backups set what so ever.
I looked at change log of I need something specific, there were changes in docker compose file. Did my best effort to make it succeed.
My worst case scenario was that I will have to import everything again and made sure I have all my labels, tags and settings backed up.
Nowadays I'll just snapshot the whole VM in Proxmox.