Seems to be a Firefox Bug: https://old.reddit.com/r/whatsapp/comments/15tgoau/cant_post_links_anymore_using_whatsapp_web/jwl5dmy/

Direct source: https://github.com/webcompat/web-bugs/issues/125920#issuecomment-1682993012

On Android at least, Firefox PWA’s don’t seem to support registering system-level things (like ‘Share To’ handlers) - you need to use a Chrome PWA for that…

No Japanese :(

I think this “improvement” is pretty poor - If I’m interpreting your post correctly, I think you can set:

browser.download.improvements_to_download_panel false

in about:config

For me:

browser.ctrlTab.recentlyUsedOrder: False

browser.tabs.insertAfterCurrent: True

dom.popup_maximum: 100

browser.download.improvements_to_download_panel: False