As described in the community thread below, downgrading a JDBC driver under `lib/jdbc` had no impact on the API Services deployment (kept failing with Java unsupported version error), even after cleaning all DOcker images (including base images) from local and remote image registry. The old Jar file was still being included in the Docker image built while deploying the API Service. I found out that the root cause was a tmp/cache data under DATA_DIR/tmp/api-services/ which seemed to accumulate the Jars that I had tried (the newer buggy version and the old one).
My suggestion is some smarter mechanism for cleaning this "cache" under DATA_DIR/tmp/api-services/ . Actually, I guess it might be very helpful in some scenarios (otherwise DSS won't create it), so maybe these scenarios should be revalidated together with this new scenario that I'm raising here.