alright let's see, first of all i have to say, you are right, the gloss was not the problem, i think it's the min spec color that is too high
with non-pbr textures, using gloss and spec overwrite 0, you can see that all the details from the diffuse texture are completely washed out, despite there should be no reflection at all:
without reflection (just because of the angle), how it should actually look with reflection and gloss 0, even when in the angle from the screenshot above:
still non pbr textures, no overrides used, so default value for gloss -> way too high!
spec color set to 0, still way too much just because of the default gloss
now WITH pbr textures, look how extremely washed out this looks because of too high reflection, despite the texture having almost no spec and gloss for this part of the texture, this is my orignial problem i was complaining about
the same pbr texture with gloss and spec set to 0, this is a completely black diffuse map, so this represents the darkest possible color you can have, way too bright!
upload of the model will follow soon btw!