All linux apps I've tried for WhatsApp are just electron behemoths wrapping around web.whatsapp.com anyway, and have pretty poor performance and reliability. Ferdium is pretty neat and I used it for a while on my tablet where screen space was at a premium so having multiple services in a single place was appealing, but it's bulky and slow and power-hungry.
I've ended up cutting out the middleman and just using ungoogled-chromium to "install" a PWA for WhatsApp. It opens in its own window with most of the browser UI hidden, so it almost feels like a dedicated app, but your browser extensions are still there and working. It still doesn't allow voice or video calls, but it runs a lot better and more consistently than any 3rd party app I could find.
I actually use this for several things - WhatsApp, Discord, and Netflix are notable examples - with each having its own separate profile to sandbox them from each other, and from the default profile that is used on the odd occasion I directly launch Chromium as a browser. You need to create a new profile first, then visit the desired site and "install" it.
Note: ungoogled-chromium needs some additional tweaking if you want to install extensions from the Chrome Web Store; if you visit the CWS straight away it won't let you install any. Also, extensions aren't shared between profiles (for good reason) so you need to reinstall any you want whenever you make a new profile for a new PWA.