Notification Controller
I can't see the notification controller when I pause or play the music. I only see the controller after changing the volume. Can you fix this issue?

Are you using the shortcuts plugin?
If so, Is the Override MediaKeys option enabled?

~~Weird because it works for me.~~ EDIT: im dumb and wrote that from memory
Can you check that you're actually using the normal media play/pause key?
In https://keycode.info/ it should show 179 (play/pause) when you click the button
Also what happens if you press next/previous mediakeys? Does it show that notification?
(176/177 keycodes)

Windows only show the volume OSD when changing volume
so play/pause/next/previous wont show that OSD, its just windows behavior
you can search google for "Windows volume OSD" and see for yourself. so there isn't actually any bug here (you can also try any other music app and see it has the same behavior since its the OS that controls this)
But if you want, you can use the Notifications plugin
and if you also want to be able to control the music from the notification, enable Interactive Notifications
its very similar to the volume osd but shows up on play/pause/next/previous track
(if you want it to show on unpause then enable unpause notifications
When I create web app with edge browser, there is no such problem like this..

this is from web app on edge browser
and this is from original spotify app

You are right, this is really weird because it used to work.
After lots of debugging, I arrived to the conclusion its because of Electron.
Thank you for reporting this here, I will report this to Electron's team
EDIT: an issue already exist in Electron's repo about this https://github.com/electron/electron/issues/32518 i've added a comment there, hopefully they'll fix it 🙂