We presently test the following in the internal CI matrix:

1. Oracle 12.2.0.4 CDB
2. Oracle 19.3.0.0 CDB
3. Oracle 21.3.0.0 CDB

We should at least add 1 non-CDB mode to the matrix to avoid problems as was found in ORA-5281 where a specific change that was adequately tested and worked on PDB installations failed on non-CDB enabled environments.