I've been a subscriber to the 'refs hate us since liverpool' conspiracy theory.
So, out of curiosity, I went through and looked at all the cards we've had since the start of the season.
4 1 3 3 6/(7 for SHU) 4 5/(7 for LIV) 3 2 1 5 (Romero red against CHE) 3 0 4 3 1 6 (Biss got red against NFO)
(4 1 3 3 6 4 5 3 2 1 5 3 0 4 3 1 6)
* I've counted straight reds as two cards. I didn't cater for a straight red following a yellow.
** We usually are only 1 or 2 cards better or worse off than our opposition and that has been consistent since the start, no change that I can see. I don't think there were any cases where we were 3 or more cards different from our opp.
The bottom line is that we've done no worse, card-wise since before LIV. We've generally been carded a lot this season.
But, despite this evidence, I still think we've been on the receiving end of some shocking decisions and that doesn't show up in this data. We've also been learning how to do the high-press and that's resulting in a lot of reckless challenges, so I'm sure our oppos feel the same way about some of the stuff we 'get away' with.
EDIT: Here's a chart with moving average for reference.