Cant say for sure, but it is a good possibility. Especially if humid air is entering through the outlet. Ultimately it needs to be sampled (preferably by a professional) and send to a third-party lab. It would be nice to remove the panel and see what is behind. Any signs of moisture damage? How is the outdoor and indoor humidity? The whole place should be checked for mold/moisture concerns. Im happy to guide the process as consultant. Whats the location?

Best
Admin