I'm posting this here as suggested on this issue
CaffeineMC/sodium#2653

I believe it would be nice if fabric rendering API could provide a fix for this vanilla bug which makes any light emitting block not have ambient occlusion/smooth lighting.

Furthermore such an implementation would need to provide a way to have said smoothing not applied when blending the target block face (say a lantern with light level of 5) to surrounding lower ligh blocks so not to create darker edges on the block itself (which would make little sense on a light emitting block). I believe this is the reason vanilla disabled AO for these blocks. Instead the smoothing should only happen when belendig wo neighbor blocks having a higher light value.

This might mean to conceptually separate AO from smooth lighting but I'm not too sure about that