how do I disable apple music blending songs on ios26.1 release candidate

Release Candidate? We are beyond the RC for iOS 26.1 and the official release version is a different build number. First make sure you are using the correct version and not one that was installed on your device due to the Beta Updates being selected.

Then see what you have in Settings for your Song Transitions here. It can be turned off completely or set with different options:

How to turn AutoMix or Crossfade on or off in the Apple Music app - Apple Support

To disable Apple Music from shuffling your songs, open the Apple Music app, tap the player at the bottom, and tap the "queue icon" in the bottom right corner. Inside, you can disable shuffle by tapping the button on the far left.

Queue icon:

Shuffle Icon:

If you don't mean shuffle, but Apple Music's new "mix" feature, go to:

Settings > Apps > Music > Song Transitions > disable