Agreed. I had no success using ProtonVPN on Lunix Mint and customer support told me it's not a supported OS, which contradicts their support page. Mainly due to this I switched to Ubuntu and again could not get the Linux app to work, but I managed to get it running with OpenVPN.
Aside from this, their services are fast and reliable and I have no issues on other operating systems.
Ever since ive made the switch to Sway on my laptop i have been completely unable to get the thing working again. I havent tried in a couple of months, but it was a known issue then