It is brown rot. https://pnwhandbooks.org/plantdisease/host-disease/cherry-prunus-spp-brown-rot-blossom-blight-fruit-rot

The cause isClimate Change and the age of your trees.

Replace your trees.

LOL!! Cherries have been getting brown rot since time immemorial - has nothing to do with climate change or age of tree (even very young trees can get it)!!

And there is not much doubt it is brown rot. The dead, brown hanging flower remains and moldy fruit are classic signs of this extremely common prunus disease.

Check with you county extension agent or what ever the equivalent office is in your area

You could also google "Cherry Brown rot:"

https://www2.gov.bc.ca/gov/content/industry/agriculture-seafood/animals-and-crops/plant-health/insects-and-plant-diseases/tree-fruits/brown-rot-of-stone-fruits

Depending on where you are, OP, it could be due to the last three years being wet. That's what we've been going through where I live. I don't have any cherry trees but it's hard to grow certain things which normally do well (or well enough).

Whereabouts are you?