I removed the seat post, and there is a brown residue on the post.
I applied clean grease when I fitted it recently.
Looked down as best as I could with a torch, doesn’t look like there is a severe corrosion issue, but there is a discoloured appearance to the inner surface.
When I get my other frame back from being powder coated, I will strip and contact someone to hopefully address the issues.
The paint is pretty solid on the outside, it’s not flaking or falling apart yet.
Too nice a frame to take a chance with.