When 2 redstone dusts are placed one block vertically apart, one of them changes its model. When a hopper is placed above that redstone and the other redstone is broken, the first one retains it's different model.

It's only a visual glitch. When the bugged redstone is right clicked or updated in any other way, it fixes itself. It also fixes itself when the world is closed and opened

I've tested this in 1.20 with vanilla MC.