Muffon. It’s not a Spotify Client but it does play music that comes from Spotifys library along sides Deezer etc. It’s super good imo, I don’t even have a Spotify subscription anymore due to it, cuz it’s that good, thought you can only use it on PC/Laptop atm though.
I’ve been using Hyperpipe though for a while on my phone, which has a PWA, which has been working super well since BeatBump started to not work for me, alongside teething problems with using Spotube.
There was Blackhole player too but that been dead for a long while now.