“Much” is for measurements of non-integer amounts, like liquids. You can’t have “five water”. (unless you stick a defined measurement next to it, like “five cups of water”)
“many” is for things that can be counted in whole numbers, like tags.
It was a puzzle. You had to guess who the artist (of the framing pic) was, after they hid their identity uploading it. They gave clues to their identity in the tag list.