You are free to use this Script Tested on 5.41.0 Vanilla Pmmp no guarantee it will work for ever, when PMMP decides to change the GarbageCollectorManager.php, this will most likely break Usage on own Risk!
I made this script, since i was annoyed by the Garbage Collection Logs in Console, so it Comments out the Logger->info part in the GarbageCollectorManager Class
also advantage of this Script is, that the GC-Logs arent saved in server.log
Now The big Question: how to apply this if this isnt a plugin?
Head to Pocketmine-Mp Github Repo, and download the Source-Code, or a fork of pmmp (not tested, but might work on Nethergames multiversion pmmp) put it in the folder where u want to build Pocketmine-MP.phar
Download GCR.py (short for GarbageCollectorspamRemover) and put it also in the folder
(on my local pc i used the old File name my bad)
open cmd and run "py GCR.py
Result:

download The Pocketmine-Builder
and put the bin folder u use for ur Pocketmine Server (depending on OS!) in the path

run it with "py Lite.py"
open then the output folder, where u will find ur Build Pocketmine-MP.phar with disabled GC Spam.
The downside of this approach is, that u will need to repeat this process each Pocketmine Update, but this is the only working solution i found after some brainstorming without nuking the asyncworkers

