dont get me wrong, I like the extra performance, but every single alternative whatsapp client has the same issue where it's missing enough core features that you end up needing to go to the browser version often enough to be a nuisance and I end up just using the browser instead (which I hate, I really really would prefer a performant client instead!)

Having also been through a similar journey, which features are missing from this one?

I use this:

    $ cat $(which whatsapp)
    #!/bin/dash
    # A kiosk is full-screen by design. You need to go to about:config and toggle
    # full-screen-api.ignore-widgets to true to prevent our window manager from
    # creating an actual full-screen window.
    # Additionally, you need to set the name to "kiosk" which will set the app id
    # under sway to "kiosk" so that in sway you can disable full-screen on
    # startup.
    firefox --name kiosk -P whatsapp --kiosk https://web.whatsapp.com/

Feels like you're just a serial complainer.