Interesting, never heard of it. I've been using Affinity since ~2017.
EDIT: apparently my enthusiasm is outdated. I just tried to load the site in Firefox [latest version] and got the following error:
"Your browser is too old (no WebAssembly). Please, update it."
What a shame!
>Perhaps you should update.
Ahem.... >I just tried to load the site in Firefox [latest version]
Fixed now, anyway. See above ^^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.
Photopea just works.