Who starts?

[Inma11]

Before each one started once.

Does anyone know why now the same person starts many times in a row?

Thanks.

[thoun]

It's random, so you can have a streak of luck or bad luck.

[Raymond-L]

In round 1 the starting player is obviously random (unless it's a rematch). In round 2 and 3, whoever took the last card in the last round becomes the new starting player. That being said, the distribution of starting players is close to random, since the players have almost no control on when each round ends.
e.g. In 25% of games the same player will be going first in all rounds.

[Inma11]

Thanks!