Why isn't it working anymore and what does LibStub got to do with it? LibStub is still there and works! It is just telling the devs to remove it where not needed.
LibMarify
LibAddonMenu-2.0
These are the dependencies involved into the addon. LibAddonMenu works without LibStub if you change local LAM = LibStub("LibAddonMenu-2.0") in your addons code to
local LAM = LibAddonMenu2
Not sure about LibMarify but as I wrote above: LibStub still works and can be used so this shouldn't be a problem with LibStub here if the addon is brolken
Edit:
Even though LibMarify says it is optionally using LibStub it doesn't in it's code anymore!
Just edit the LibMarify.txt file and remove this line:
## OptionalDependsOn: LibStub
Save and LiBStub usage in the library is gone.
Edit2:
Guild Donate does not use LibStub in any place so it should work if you enable the 2 needed libraries. It alreadys stripped LibStub.
The 1 line above in my first eit should be all to remove this addon from a list of "LibStub" users.