Problem with uploading in Proton Drive Android

The uploading functionality—either a file or multiple files—is broken. It's stuck on "Waiting to upload" forever. And files are not guaranteed to be uploaded.

Seriously, don't people at Proton do testing the Android app? I have to switch to use Firefox for using the web app. It's inconvenient, but that's the only way that uploading to Proton Drive in mobile works.

What's the best way to quickly raise this issue to Proton: Proton Support or Customer Feedback?