DB 18.104.22.168 will likely work. Officially, it's not supported anymore and the specific version hasn't been tested. 22.214.171.124 is the version of 11g that is currently supported.
Your issue is due to not setting the Oracle SQL compatibility level to 11. Oracle EF Core will assume you are using 12c or higher and use the higher version's Oracle SQL syntax. You can set the compatibility level by using, such as the following:
optionsBuilder.UseOracle("User Id=hr;Password=<password>;Data Source = inst1", b =>
Thank you very much
Now that I know the answer, I find plenty of stackoverflow posts that recommend this, I just did not find them yesterday