Chargers wanted to get their run defense in.
Play clock had run down, Raiders were about to snap the ball
PS Robbie Gould was the SF punter today
It sure looked to me before the timeout that the Raiders were happy to run the clock out. Yes they were in FG range, but why risk a blocked FG at that point.
But after the TO, they knew they’d better try to at least get the first down and get closer for the Field Goal.