AllTheLeaks is reporting objects the server cannot free
What it looks like in your log
[AllTheLeaks] Memory Leaks detected:
What causes it
The AllTheLeaks mod is printing its leak report. Objects the game has finished with are still referenced by something, so garbage collection cannot reclaim them and the heap fills until the server stalls or dies with an out-of-memory error.
How to fix it
The bracketed name after each leaking type is the mod holding the reference; update or remove those first, minecraft itself rarely leaks. Cloned players point at a respawn or dimension-travel bug in a mod. Until it is fixed, restart on a schedule before the heap fills, and run /atl force_refresh after players log out to see which mod keeps growing.
Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.
Check your own log