@CrazyTom2k2 Obviously you have a lot of experience with samsung Devices and know you are skilled with a lot of Tech issues. However are you using a lot of the optimisation settings that @LiquidSnake describes. Certainly I put some apps in to sleep or Deep Sleeping Mode and best to turn off connections when they are not needed. Personally though I am not a fan of constant dark backgrounds and think you want the balance of the best experience/battery life. However the battery is the a gripe for several users and one thing practically everyone would like to see improved.
Personally I use Amazon Music more than spotify , however some users have reported that Spotify can be a battery hog in some situations with Spotify Connect being more of an issue. See here https://www.tuneskit.com/spotify-music-tips/fix-spotify-battery-drain.html
Realise the concern though I think there are factors to consider and updates can fix some battery issues. For me it would be the overall enjoyment and experience with the Smart phone, though you obviously want sufficient and hopefully improved battery life.