It’s most likely collation related, where the original posts table has ended up with a different collation than new tables are configured to use.
There’s a related thread here with a potential fix, although I haven’t tried it myself Unable to upgrade Ghost from v4.2.0 to v4.3.0 (CASCADE - UNKNOWN_CODE_PLEASE_REPORT) - #56 by jebarjonet
The problem is also mentioned in the docs Resolving a misconfigured MySQL database with Ghost - Ghost Developers