The MLS Disciplinary Committee has suspended FC Cincinnati defender Matt Miazga for three matches and issued an undisclosed fine for "misconduct" following his team's playoff win over the New York Red Bulls on Nov. 4.

A source with knowledge of the league's investigation into the incident said that Miazga was suspended for gaining unauthorized access to an area reserved for match referees.

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When reached by ESPN by telephone, Peter Manikowski -- president of the Professional Soccer Referees Association, the union that represents MLS referees -- referenced the referees' match report from that night, which said that about an hour after the match Miazga entered the referees' locker room uninvited, used foul language and acted in an aggressive manner.

At the time of publishing, FCC has not responded to phone calls requesting comment about the suspension.

Miazga, who was recently named MLS Defender of the Year for 2023, also received an undisclosed fine, and must go through a behavioral assessment as part of the league's Substance and Behavioral Health Program. MLS said in a statement that Miazga "may petition for a reduction in suspension based on continued commitment and compliance with any recommended treatment programs."

The suspension effectively ends Miazga's campaign, ruling him out of Saturday's Eastern Conference final against the Columbus Crew, as well as the MLS Cup final, should Cincinnati get that far. Any portion of the suspension that isn't served in 2023 will carry over to the 2024 season.

In the second match of FCC's first round playoff series against the New York Red Bulls, Miazga was booked for dissent after referee Victor Rivas had blown his whistle for full time. Miazga, a former Red Bulls player, was then cautioned again when, after converting his attempt in the penalty shootout -- which FCC ultimately won -- he blew kisses and said "I love you" to Red Bulls supporters.

Combined with a yellow card Miazga received in the first match, the defender was suspended for the Eastern Conference semifinal against the Philadelphia Union, which FCC won 1-0 last weekend.

The aforementioned source told ESPN that video evidence shows that after the match, Miazga entered an area reserved for referees in a bid to speak with Rivas.

In the immediate aftermath of the match, differing descriptions of the incident emerged. In a social media posting on X, formerly known as Twitter, the Professional Soccer Referees Association, the labor union that represents MLS referees, stated that an unidentified player "was forcibly removed by stadium security while acting in an aggressive & hostile manner."

Multiple sources confirmed that Miazga was the player referred to in the posting.

A source with direct knowledge of the incident confirmed a Cincinnati Enquirer report, contending that stadium security wasn't involved, nor was force required to remove Miazga.

Prior to its semifinal match against the Union, FCC manager Pat Noonan told reporters: "It's an hour and a half after the game, [Miazga's] got a pizza box in his hand. I think people have this notion that he was in his cleats, running into that room. It's been fabricated, what happened."