Suds
Homescapes Guide
What are Suds in Match-3 Elements? These are bubbles that you have to remove by clearing pieces beside them so they can be popped. However, they have a feature that can turn them to an obstacle that is hard to clear.
Suds will multiply and block more tiles if you make a move that doesn't remove any suds. So you'll need to think carefully about which piece you'll clear, try to remove the suds before they cover majority of the puzzle.