[DennisAleynikov]

yeah I'm also on firefox and its working for me. this shouldn't be a problem mozilla supports webassembly

[Normille]

Yuu're both right. For some reason I had:

about:config > javascript.options.wasm > FALSE

Could be that's the default. I certainly don't remember disabling WebAssembly at any time.

Photopea working fine in FF now.