I have their paid VPN. The browser version of Proton VPN is limited. It's sad. I don't like talking like this because I like their service and speed, but there are so many things missing in all their apps, such as the Windows version, Android version, and the one in browsers.

Split tunneling is lacking on all devices and none have the same features. The one on the browser has the one I want, by website, but you can't include. As in, if you only want it to run on that website. You can only exclude so that it doesn't run on that website.
The one on Windows doesn't have website but IP or apps. You can include/exclude there but we desperately need the ability to add websites there and to decide per website/app/IP if we want to include or exclude. Same on the browser extension. Same on Android.

Here in Firefox, it's also missing a favorites list and the ability to choose a default. Same on Chrome/Edge. All 3 of their apps/extensions look different and behave different and have different settings. Really bad design.

None of our settings sync so you have to set it up each time in every browser, phone, computer OS.

Missing other information and settings.

Considering the number of clients they have, servers, and money they're making, they should easily have the budget to improve and streamline them all.
Will edit review after they update.