Question need help with lightmap

hi need help. baked a lightmap in unity and at one point everything became terrible. at first I thought they were overlaps. but the problem is something else

 

It's difficult to say (because I am not an expert). Here are some things I try:

Clear Baked Data (stale data can cause this stuff, especially after an update)
Disable "Compress lightmaps" temporarily to see if it has an effect
Go to the inspector setting for any any normal maps and change compression to none in override settings
Check all models and make sure "Generate lightmaps" is enabled if you do not have 2nd set UVs from your modeling package exported with the model
Check lightmap scale on models and make sure they are decent size (usually 1)
Increase Max Lightmap Size. I find that 2048 works better for the atlas size and reduces calls too (just a preference as most systems, even mobile can handle 2k lighmaps)
Check Shadow quality
Make sure your objects are not huge (in actual size)
I achieve good bakes on rooms 10meters cubed, all objects set to scale 1, and lightmap resolution set to just 10
Try decreasing max light bounces and see that helps, I use 3 or 4.
Also check the thing that is actually causing the issue, which could be like 40 other settings not listed above.
Again, I'm no expert, I just have years of frustration playing with lightmap baking in Unity