Spotify doesn't remember size and position [FlatPak]

[mixmat]

Operating System

 Mint 20.3 on Cinnamon

My Question or Issue

1. Spotify/1.1.68.632​
2. Brief description of the issue:

Whatever the size I set spotify to, on next start, it will fall back to the same size

1. Steps to reproduce the issue:

• Install Spotify from FlatPak
• Launch Spotify
• Resize Window
• Close it
• Launch Spotify again

6. Attach the spotify-dump.txt ( $HOME/spotify-dump.txt ) from Advanced troubleshooting 4.

​╰─ flatpak run com.spotify.Client 
/app/extra/bin/spotify: /app/lib/libcurl-gnutls.so.4: no version information available (required by /app/extra/bin/spotify)
[spotifywm] attached to spotify
/app/extra/share/spotify/spotify: /app/lib/libcurl-gnutls.so.4: no version information available (required by /app/extra/share/spotify/spotify)
/app/extra/share/spotify/spotify: /app/lib/libcurl-gnutls.so.4: no version information available (required by /app/extra/share/spotify/spotify)
[spotifywm] attached to spotify
[spotifywm] attached to spotify
Gtk-Message: 15:45:03.567: Failed to load module "xapp-gtk3-module"
/proc/self/exe: /app/lib/libcurl-gnutls.so.4: no version information available (required by /proc/self/exe)
[spotifywm] attached to spotify
libva error: /usr/lib/x86_64-linux-gnu/dri/intel-vaapi-driver/i965_drv_video.so init failed

 I also attach my prefs file (/home/mm/.config/spotify/prefs), in which I tried to override size & position.

On each startup, position is 0,0 and size is w800*h630.

And since it is quite small, I'm pretty much forced to resize window if I want to change playlist or queue.

Is it a limitation from the FlatPak ?

Best regards