I was able to reproduce this situation with Flow in 1.
Reducing Flow to zero (0) the problem (whitening) no longer happened.
Reducing Flow to zero (0) the problem (whitening) no longer happened.
.....
Samj Portable - Gimp 2.10.28 - Win-10 /64.
Samj Portable - Gimp 2.10.28 - Win-10 /64.