Are common potions of healing considered magic items?

I just had a session and there was an argument about this. In the DMG page 187-188 it shows potions of healing in the magic item section. In the PHB page 153 it says they are magical. On DNDBeyond it is considered both magical and mundane when you go to add equipment to your character. One player was saying they are always magic items and another was saying that according to dndbeyond it isn’t always a magic item. Which person is correct?