Hello!
I wanted to provide a quick update regarding this issue. We have discussed this issue internally. As noted in another thread, which @AcidArrow has linked to, it is caused by 32 bit floating point precision errors. This means that large scenes, and objects placed away from world origin (0,0,0) will exhibit lightmap artifacts.
We are planning on addressing it as part of the upcoming unified baking backend work. We cannot provide the ETA, unfortunately.
In the meanwhile, you could try the workaround which [mention|GDKOBl5S4JVJykdCMcXmkg==] had suggested in a different forum thread :
The stripe artefact is is likely caused by 32 bit float point precision issues as AcidArrow said, so increasing push off on the object via Lightmap Parameters could be a workaround. Unity - Manual: Lightmap Parameters Asset
I hope this helps.