I have been trying to get the CMOD 10.5.0.10 from Fix Central.   After a couple support tickets IBM finally came back with this information a few days ago:

IBM has identified an issue with CMOD 10.5 FP10 and is actively working on corrective fixes. Until the revised FP10 is available, IBM recommends that customers only deploy up to CMOD 10.5 FP09. IBM will share an updated FP addressing the issue as soon as possible. In the meantime, IBM will work closely with you to investigate any reported issue reported and will either confirm whether it is reproducible in FP09 or provide a targeted fix if required.

There is currently an aim to release FP10 in May. This is tentative and could change.

     As part of regular maintenance, I am planning an upgrade to the latest fixpacks for an RHEL 8 system with CMOD 10.5.0.6 and DB2 11.5.8.   IBM DB2 support confirmed DB2 11.5.9 released November, 2023 was the last DB2 11.5 patch and suggested I go to DB2 12.1.   IBM CMOD support said they support DB2 12.x, but CMOD hasn't been certified with DB2 12.x which means IBM Passport Advantage doesn't give me the option to download DB2 12.1 with my CMOD license.  IBM CMOD support confirmed CMOD 10.5.0.9 will be released in April, 2025 and IBM Passport Advantage support passed this along: "In discussion with the CMOD Chief Architect yesterday, the plan is for CMOD 10.5.0.9 to officially support Db2 12 by the end of 1Q-2025.".    In April, it looks like we should have access to download CMOD 10.5.0.9 and DB2 12.x from IBM Passport Advantage.