i can also confirm its related to xmltv epg data …
my experiences are pointed here, actually it came more or less after the fix for the file usages in /tmp …
now no more docker size ballooing, therefore RAM 
- no xmltv guide (using PMS guide), normal RAM usage (still alot compared but stable)
- external XMLTV, RAM increases each day ~ 1 gb … when i limit the docker RAM to like 2gb
Plex crashes after the 2nd day … if not limited it ll fill up and my system will start quitting jobs …
both tests with same tuner setup, so only difference is the guide source …
of course the PMS guide was not as complete (cause only 1 source allowed) but i left it running for some days and Ram did behave normally.
