this AO looks bad, Can it be fix?

At least for me this is only happening with experimentalForgeLightPipelineEnabled = false in forge-client.toml. Even though it says "experimental", it isn't really experimental at this point, you should enable it.

No idea. Do you know how to fix it?

I only know that this AO follows the model rotation, it shouldn't be.

I can't find the original, but I think I saw a similar problem on a Forge issue, which revealed the issue is that the order of the vertexes matters for retrieving AO. So when rotating all the quads need their vertexes cycled appropriately :/