I can no longer give the Daily Mixes feedback by disliking a song (or artist) the button is simply not there anymore. They are still available for Discover Weekly and Release Radar.
Problem exists both on windows 10 desktop app and on Android.
I tried to sign-out, sign-in on the desktop however it did not help. Also tried uninstalling and reinstalling - it doesn't work.
I notice a similar post back in May has been marked as "FIXED" - IT IS NOT! FIXED!!!! So it appears this problem has been around since May. Meanwhile the songs in my Daily Mixes are getting worse and worse ...
They said somewhere that DailyMix is supposed to work this way now. Maybe you have seen that post. DailyMix(DM) Now: 6 list, 50 songs each, not endless. I noticed too that the songs are getting worse, because Spotify calculates something that you maybe like this and that and add them on DM. Sounds like a try to get plays.. For new artists there are Discover Weekly.
In the good ol' days.. daily mixes include the songs / artists you have played earlier, not weird suggestions. Spotify: Fix the Daily Mix algorithms back like they used to be.