There has always been randomness but this is a new thing. Differences in tactics aren't enough to explain such a consistent trend either. I looked at last two league rounds, the home team had more possession in only 2 of 14 games, with a red card for away team involved in other of them.

So at least in my server, there's definitely a home team possession disadvantage, and I think this is an unintentional bug. Interesting if other servers don't have the same.