Just loaded an old Core backup from 2020 and was informed about migration in version 27.1.0, is this something i need to do soon?
Yes if you want to use the future versions of Bitcoin Core starting v29.0.
You can follow this issue in bitcoin core's GitHub repository to see when it'll get implemented:
https://github.com/bitcoin/bitcoin/issues/20160As for migrating, the process is automated and non-destructive since there'll be a backup file to be created and you can always created a backup before deciding to migrate the keys to a descriptor wallet.