The San Francisco 49ers have endured the absence of numerous players due to injury all season.

On Thursday, they were down a player who merely didn’t want to participate.

San Francisco coach Kyle Shanahan said linebacker De’Vondre Campbell wouldn’t go in the game in the second half as the 49ers fell 12-6 to the Los Angeles Rams in Santa Clara, Calif.

Campbell, 31, had made 12 starts in 13 games this season prior to Thursday, when Dre Greenlaw took his position after recovering from an Achilles tear he sustained during the Super Bowl in January.

With Greenlaw experiencing foot soreness, Shanahan asked Campbell to take over in the third quarter.

“He said he didn’t want to play today,” Shanahan said, adding that Campbell gave no reason.

Shanahan said, “When someone says that, you move on. You don’t deal with that anymore. That’s somebody who doesn’t want to play football, that’s pretty simple. I think our team and myself, we know how we feel about that. I don’t think we need to talk about him anymore.”

Niners tight end George Kittle said, “I don’t like distractions on the sideline. I think it’s ignorant and I think it’s just dumb. It’s just stupid. It’s very immature. I just don’t see how you can do something like that to your team.”

San Francisco cornerback Charvarius “Mooney” Ward said of Campbell, “He’s a professional, he’s been playing for a long time. If he didn’t want to play, he shouldn’t have dressed out. He could have told them that before the game. … It definitely hurt the team because (Greenlaw) went down and we needed a linebacker, you know? … So for him to do that, that’s some selfishness.

“He’s probably going to be cut soon, so it is what it is with that.”

Campbell, in his first season with the 49ers, has 79 tackles and two passes defensed. He previously played for the Atlanta Falcons (2016-19), the Arizona Cardinals (2020) and the Green Bay Packers (2021-23). He made first-team All-Pro in 2021 when he had 146 tackles, two interceptions, two forced fumbles, one fumble recovery, five passes defensed and two sacks.

In 128 career NFL games (122 starts), Campbell has 858 tackles, seven interceptions, eight forced fumbles, three fumble recoveries, 30 passes defensed and 9.5 sacks.