Darwin Nunez was shown a red card during Liverpool's 1-1 draw with Crystal Palace after he head-butted Joachim Andersen.
The referee's decision is not widely debated, even though the contact between the players was not too strong.
Nevertheless, some fans vented their frustration at Andersen who revealed receiving abuse and death threats.
"Got maybe 3-400 of these messages last night. I understand you support a team but have some respect and stop acting tough online," Andersen posted on his Instagram page before sharing the screenshots of some of the messages. "Hope Instagram and the Premier League do something about this."