Looks like pam snuck an extra type of tree in there, so acorns won't grow in the pots yet... Relevant item ID's:

• pamhc2trees:acorn_sapling
• pamhc2trees:acornitem
• they grow on oaks

Thanks for letting me know about this. It looks like they actually added several new saplings. This should be fixed in 4.0.13 for MC 1.18.2. I will look into compatibility for 1.20.1 soon if it's not already supported. If the CurseForge link doesn't work give it a few minutes as the file was just uploaded and they need time to process new files.

This is now fixed in 1.20.1 with 9.0.8.