A competitor used a stickerless cube with a "PVC coating" on each colored part. The puzzle was accepted at the competition.
Similar cubes with non-transparent (black) stickers have previously been allowed, and the WRC has concluded that the PVC coatings do not give the competitor an advantage that Regulation 3d) and Regulation 3h) are meant to prevent.
Therefore, the WRC has decided that it is reasonable for these puzzles to be permitted.
The WCA Regulations will be updated to clarify this.