I posted the original tweet. The problem is with a spot color channel, which I created in the first place by picking a color name from a color book 20 years ago. Now, the on-screen color (PANTONE 130 CVC, an old color name) goes black in Photoshop 2023, but is still a recognisable yellow in an older Photoshop 2022. Without the screen reference, you don't know what it's supposed to look like, so designers working with multiple spot colors could have a tricky time.

More info in this video: https://youtu.be/OBs2-2KcN-w