I have installed gmail-desktop. The version is 1.5.1. However, I receive an error message stating thet the browser is not safe, and it does not allow me to get into the gmail account.

That’s funny, I must have downloaded the same version two years ago, and it worked really well up till early 11-2022. It says I’m connected to my gmail account, and shows an indication of mail when the inbox is toggled, but it won’t open the inbox, or any other file I had set up, for me to view the email. I think this was because of some “upgrade”. I run it on a Linux Mint machine. Did you ever get yours to work?

you should try to report it at: