The Oracle database for Content Manager and Tridion Sites 10, can see many sessions left that have open temporary/abstract CLOBs.   This leads to high PGA memory usage and you can see errors like ORA-04036: PGA memory used by the instance exceeds PGA_AGGREGATE_LIMIT.

A hotfix is available to fix this issue - CM_10.0.0.39912. This now explicitly releases the temporary CLOBs as recommended by Oracle.  It is available via FTP as per:

Where can I find hotfixes for SDL Tridion Sites/Web?

Not all temporary CLOBs are returned to the application as they are not explicitly released in the application code.