https://www.facebook.com/PianoTilesFans/videos/1026433540803042/
Interesting, they seem to be differently measured than slider/hold notes; they're worth 2 points for what seems to be the same amount of beats to a hold note next to it (same beats, slider worth 3 points and swipe worth 2 points).
See 0:19 - 0:20, and check the point count. Any confirmation on this?