It does look like they develop a sort of "rust" through exposure to sea air [0], though what effect that has on low-observability remains to be seen. 0: https:

It does look like they develop a sort of "rust" through exposure to sea air [0], though what effect that has on low-observability remains to be seen. 0: https://www.thedrive.com/the-war-zone/44067/the-f-35cs-radar-absorbent-skin-is-looking-pretty-rough-after-months-at-sea https://www.thedrive.com/the-war-zone/44067/the-f-35cs-radar...