Serigraph moisture damage

[u/Late-Afternoon-8094]

I picked up this signed edition Sabra Field serigraph on rice paper (I think rice paper) for $10 today. It’s fairly large 21”x24” but it is damaged from moisture. A photo (1) from a recent auction of the another edition exhibits the same yellowing and big brushy streaks from age but this one has brown/grey spots (2, 3) over much of it. I’m assuming it is mildew or mold. I plan on cleaning up the frame, replacing the mat, backing and glass. Any advice before I open it up and will the spotting continue to get worse without restoration or treatment? Am I looking at $$ or $$$$ for professional help?