I’m not sure quite how to explain this, but the “Now Playing” widget in the MacOS menu bar, which usually shows album artwork, back/forth/play buttons, and a progress bar, doesn’t appear properly for Deezer.

This is what it looks like for Apple Music or Spotify:

While this is what appears for Deezer:

The lack of album artwork is a minor quibble that doesn’t really matter, but the progress bar is pretty important. I use it very often when I’m on another app or working on something else. It’s frustrating that Deezer, a dedicated music app that I’m really enjoying otherwise, is lacking these basic functions and has the same poor integration with playing controls as Firefox does.