The N.B.A. has fined Nets guard Kyrie Irving $50,000 for violating the league’s health and safety protocols after a video emerged that seemed to show Irving maskless at a family birthday party last weekend.

The league’s guidelines bar players from attending indoor gatherings of 15 or more people, as well as going to bars and clubs. The N.B.A., in its announcement of the fine on Friday, said Irving was in a five-day quarantine but that he would be eligible to return to team activities on Saturday if he continues to test negative for the coronavirus.

But it is unclear whether he will return. Irving has been away from the team for what the team has called “personal reasons” since playing in a game on Jan. 5 Before a Jan. 7 game against Philadelphia, Nets Coach Steve Nash said he did not know why Irving wasn’t playing and that he had not heard from him. Since then, Nash has said he has been in touch with Irving, but has declined to provide more details.

On Thursday, Nets General Manager Sean Marks said he was “disappointed” that Irving was “not amongst us, not in the trenches with us.”

“I don’t want to speculate and say why he’s out and so forth,” Marks said. “I’ve had conversations with him, and I’ll continue to have conversations, and I look forward to him being back in the gym and he will address this and we’ll sit down with him.”

The Nets have started the season 7-6, a slower beginning than many anticipated considering the team’s headline talents of Irving and Kevin Durant. If Irving does return Saturday, he’ll have a new teammate: James Harden, whom the Nets acquired from the Rockets earlier this week. In December, Harden was also fined $50,000 for violating the league’s health protocols by going to a large indoor party.

This week, the N.B.A. released a stricter set of health protocols to combat a rise in coronavirus cases among players that has forced the postponement of several games. Among the new rules, players and staff are expected to confine themselves to their homes for at least the next two weeks, aside from going to practice and games, and doing essential activities.