Yes, its supposed to have a glow-in-the-dark appearance. Too bad it can't actually glow in game.

Actually, now that I think about it, due to the 1.17 update and the new "customizable light block" that was added, someone could probably run a few commands through some command blocks to 1.) Set a light block anywhere a goat is, and 2.) Delete all light blocks in a 1 block radius around it, thus giving it a real glowing effect, without a trail of glow blocks left behind.

Thank you