How long is 1 round?

[Fart Receiver]

I can't find any indicator telling me how many turns that are left in 1 round and some rounds seem to last longer than others

[thelefthorse]

A round lasts until either both players have passed, or until both players are out of cards. If you're new to the game, it is really important to learn how to "pass" -- to stop playing when you are down too many points to recover or if you are up by a lot of points and think you can either win that round outright or force your opponent to go a card or two down to win that round.

You can pass by holding down the end of turn token until the highlighted circle goes all the way around. You can only pass if you haven't played a card, used your leader ability, or triggered any available actions on the cards you have on the board.

[PoetryForAnimals]

If nobody passes the first round is 10 cards, 2nd round 3 cards and 3rd round (if first two ended 1-1) 3 cards.
But yes this can differ a lot if people pass strategically.