Your masts were detected by MPA!
RA has implemented a "mast detector" system for ASW Air / Surf platforms, but DW engine can not check whether any mast is physically raised.
So every time you are on the surface, the game assumes you have raised masts.
Solution: if you don't want to use periscope (or other mast) do NOT run on PD or shallower. You should run 1-2 meters below PD.
Go to PD only for quick checking situation.
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