Seent this on Twitter. I’ve had this happen to at least 5 pairs and the process was always the same - I’d wear, wash, think the shoes were dry, then store (not knowing shoes were still damp).
The first pair it happened to - some all suede new balances - got so screwed up I threw them away. Also happened with some 5’s, air max 97’s and some KD V’s.
You should continually check on your shoes, especially if you’ve got them in dark places.