It looks like 2021r1.1 fixes that. We have several instances of a 24/7 web app that suffered from the leak. Ram would jump from 15 megs to gigs over time… Recompiled with 2021r1.1 and the leak is gone. So you might want to try to recompile and see if it works for you.
Just be aware that there seems to be an issue if you use response.file in handleurl (see my post Handleurl WebResponse.file vs WebRequest.file change since 2021r1)