For the last year or so I consistently get errors when trying to play Spotify via Google Home devices (3 x nest mini, 1x nest hub, 1x nest hub max) and I've had enough. Issue occurs when I ask google to 'play music', when being asked to play something specific, or attempting to play from the app on my (and other) mobile phones via the cast function. This happens a good 95% of the time, with the issue randomly dissapearing for an hour or so before returning straight away... I now ask Youtube Music to play music the majority of the time as it works fine.
I've followed a number of other help topics, unlinking/relinking accounts, restarting apps/devices, recreating google home from scratch, opening port 4070 on my router, unlinking my account and leaving my wife's account linked to google home (we're on premium) and vice-versa, among other general troubleshooting options.
I don't have issues with any other app at all, as mentioned, Youtube music plays straight away everytime with no issues via the nest devices and anything else I do on the devices works completely fine with no issues.