The game may have become a draw due to insufficient material, e.g., K-KB, K-KN, and of course K-K. Chess also has a 50-move rule that results in a draw.

https://en.wikipedia.org/wiki/Fifty-move_rule

This was probably it, didn't know of this rule. Effectively a real-world "timeout" !

Might be a bug, anything in the console?

(I'm not the author of chessboardjs, just stumbled over it)