Title says it all. This does only happen if you manually place it down with sneak + place. If your absorption effect runs out and you eat another golden apple you can pick it up just fine.

Mods used:
MythicBotany-1.16.4-1.3.2.jar
Minecraft: 1.16.5
Forge: 36.1.16
Botania-1.16.5-415.jar
curios-forge-1.16.5-4.0.5.1.jar
jei-1.16.5-7.6.4.87.jar
LibX-1.16.3-1.0.60.jar
Patchouli-1.16.4-50.jar

so i have a similar issue, but my hammer vanished when i tried to pick it up, i was in a claimed chunk

Which version of MythicBotany?

1.3.2
PS: i know its old, but im on a server and cant do much about it

It was fixed in 1.3.3. Please update.

even if i update, i assume my hammer is gone for good?

Yes :(

Oh well, RIP my short-lived hammer. Thanks for your time ☺️