Referee Gil Manzano rewrote the details in the match report, as reported by Spanish newspaper Sport.
Gerard Piqué was upset after two situations in the first half.
Osasuna took the lead early in the match on a corner - wrongly awarded according to Piqué.
And just over half an hour into the match, superstar Robert Lewandowski received his second yellow card and was sent off.
So when Manzano blew the whistle at half-time, Piqué went onto the pitch to ask for explanations of the decisions.
It resulted in the 35-year-old following the referee towards the changing rooms, where he was awarded the red card.
According to the match report from Gil Manzano, Piqué said, for example: "You are the referee who ruins the most for us" and "You are a damn shame".
Barcelona turned around and won the match 2-1 after goals from Pedri and Raphinha.
But after the match, Barcelona coach Xavi was upset about the refereeing in the match.
- I had planned to replace Piqué in the second half, I had needed him.
But he was red-carded during the half-time break after tension in that situation.
We felt injustice.
We felt the referee was against us.
That's why he reacted the way he did, Xavi said at the subsequent press conference.