"This is also how I learned one way that Photoshop was for professionals and GIMP & ImageMagick weren’t; At the time (and this was years ago, to be fair), Photoshop dithered by default when going from 16 to 8 bits, while those popular open source tools did not and also did not even have good ways to do it manually by adding the right amount of noise before changing the bit depth."

Yes. Photoshop does the correct thing when going 8bit via the "Mode" menu. On the other hand, if you do "Export As → PNG" and check the "Smaller file (8-bit)" checkbox, it does NOT dither, and it produces banding artifacts.