playerctl volume controls not working correctly

[J4mStuff]

Describe the bug
playerctl volume control doesn't seem to work correctly.
When attempting to increase player volume it doesn't do anything.
Decreasing volume instead sets the volume to 100% - offset value instead of decreasing it by the offset.
Getting current volume always returns 1.0 instead of current volume.
Setting volume to specific value is the only one that seems to be working correctly.
There's no error's / warnings returned from playerctl.

To Reproduce
playerctl --player spotify_player volume 0.1+
nothing happens

playerctl --player spotify_player volume 0.1-
volume is set to 90% (it seems to always set it to 100% - offset)

playerctl --player spotify_player volume
returns 1.0000 instead of actual volume

Expected behaviour
playerctl --player spotify_player volume 0.1+
sets the volume to current volume + 10%

playerctl --player spotify_player volume 0.1-
sets the volume to current volume - 10%

playerctl --player spotify_player volume
returns current volume as a float (0.0-1.0)

Log and backtrace
Backtrace is empty after running commands above. Normal log likewise does not log any events when running those commands.

Screenshots
Probably N/A

Environment

• OS: Arch
• Application version:$ spotify_player 0.20.6
• Application features: default of installing from AUR (according to readme here it's all the features)

Additional context
Not sure what else is there to mention. The playerctl seems to overall be functional in terms of being able to communicate with the app as you can set the value directly, it's just the offsets and getting value that's the issue. If I were to guess the main issue is the volume reporting given the behavior when lowering the volume.
I wanted to map my keyboards media buttons to explicitly control this app, which is where I noticed this issue.