I Have contacted the google support via chat
I have disconnected the google home mini and the wifi for a couple of minutes from the plugs but was still not working
Then I have reset the google home mini from the device itself
On the back of the google home mini there is a small circle next to the plug side
press it for 15 sec and the device will ask if you want to really reset it
wait for the sound then it will restart again and you will have to redo the voice pairing from the google home app
Now spotify is working back
Oh my thank you so much, resetting it finally worked!! :D
Go to spotify
Go to settings
Go to connect to a device
Click on Google home
This worked for me. I hope it works for you too.
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Have a great day!