It looks like it’s using the wrong lightmap or UV channel for some reason. Did you rebake anything or import models or change the lightmap UV?
It is set to use the first UV channel for the lightmap-- change the Lightmap Coordinate Index from 0 to 1
You would also need to increase the lightmap resolution, it’s set to 64 which is too low for something like that.
Also, if you can, there’s some really small UV islands that will have issues with lighting, try to adjust your mapping and attach those back to larger pieces.
all good now
Check Recompute Normals
Increase Lightmap Resolution
Set Lightmap Coordinate Index to 1
Like Noxxan said, check the normals.