Heavy gloves are gauntlets, which certainly should interfere with a spellcaster's ability to cast spells unless they've specifically trained under those conditions.
5e is already incredibly lenient for spellcasters, allowing them to wear various armors without penalty as long as they have (easily obtained) proficiency. Spellcasters in older editions of D&D could wear armor but would have a
percent chance failure to cast spells, ranging from 5 to 40%, along with other penalties if they weren't proficient. (I'm citing pathfinder for reference; it's basically 3.5e).
