In my experience not just sometimes, but rather commonly. It often feels like the native Linux version, if it is even available, gets far fewer bug fixes - not like I can blame them, considering the far lower amount of Linux players, but sometimes I wonder why they even bother with it in the first place if they don’t want to bother with focusing on it, with how good Proton is.

Note that it doesn’t mean metadata is encrypted. They may not know what you sent, but they may very well know you message your mum twice a day and who your close friends are that you message often, that kinda stuff. There’s a good bit you can do with metadata about messages combined with the data they gather through other services.