Executing prepared statements may get slower over time

A user on Libera.Chat reported that after upgrading from 10.3.36 to 10.3.37, MariaDB started to take up more and more cpu over time.
When executing 'show processlist', many queries showed "Starting cleanup". This should not be the case as doing a cleanup for the next query is normally a very fast operation.
We also found out that most users where using prepared statements and the memory allocated per user (shown in information_schema.process_list) was much higher on 10.3.37

The suspected cause is that while executing a prepared statement, under some conditions new Items are created (creating of Item's should only happen on prepare and first execution).
Over time the Item list is growing and cleaning them up for next execution will take long and longer.

We have been able to create a test case to repeat the issue and it will be fixed shortly!