I’ve had the following case a few times already:
- start an OTB game
- play until conclusion
- one of the squares starts flashing after the game ends
In particular, for a game played yesterday i can provide more details:
- the game was initiated from the app
- played until white resigned through the app interface
- the whole board flashed for a few seconds (this is expected)
- after that, a random square started flashing with purple