Yep - a bad sign.
Mold is more than likely embedded deep in the foam.
If it were me - and do it the lowest cost - I'd get the kiddy pool out - fill it with detergent/bleach as if laundry - and deep soak the cushions - walking on them.
Stand them to drain & dry in the sun.
Mold will only progress cool & damp.
I finally made 2" plastic pipe full length from windshield to transom a foot above windshield to support tarp so it's tented steep for water run off and warm moist air escapes quickly out two large vents at top.