Getting A LOOOOT of Aberration Problems with Lightmapping

I am getting completely crazy with lightning and lightmapping in Unity, I have tried everything for two weeks or more and I don’t get any good result.
I made a scene importing a fbx room in Unity. That fbx was modelled with Fusion 360, and after that I imported it in Blender and created for every body 2 UV maps, the first one the Lightmap Pack UV and the second one the UVs. I also increased the island margins to have less problems.
I imported the bodies into unity, set them as static and increased the lightmap scale as much as I could for the most important bodies of the scene.
Some of the lightning settings are 2048 Lightmap Size, High Quality compression and Default.HighResolution Parameters, with a Lightmap Padding of 4 texels.
After doing all of this, this is what I have:

It looks absolutely shit. I am going completely crazy, I have tried everything, I have tried with Unity creating the UVs but the appearance is even worse. Please, what can I do?? This is the most frustrating thing of all my entire life

Thank you very much

Lightmapping troubleshooting guide contains some guidance on how to fix this issue. Please take a look at the following sections: