I think what we have here is confusion of the schedule. You said "they didn't run 13P in the Jacksonville game" which is wrong. Obviously you confused the Jacksonville game with the Baltimore game, even though they ran some 13 P in that game AFTER Puka was injured. Here's an article about the 13P.
McVay's Schematic Switch
"Then, with 10:02 left in the first half of the Rams’ 17-3 Week 6 win over the
Baltimore Ravens, receiver Puka Nacua suffered a sprained left ankle, and everything changed. Nacua has become one of the league’s best receivers, and with him out for any length of time, things were going to be different.
For McVay, being different meant using a personnel package he’d barely ever used before – 13 personnel, with 1 back, three tight ends, and one receiver. The Rams hadn’t utilized 13 personnel on a single snap this season until about a quarter after Nacua’s injury. In the second half, they had eight plays in 13, and all were running plays.
The first time the Rams ran out of 13 personnel, running back Kyren Williams scored a rushing touchdown from three yards out.
With a week to figure out what to do without Nacua, and a trip to London’s Wembley Stadium to face the
Jacksonville Jaguars in the meantime, McVay drastically stretched his definitions of 13 personnel, especially in the passing game. In Los Angeles’ 35-7 blowout of the Jags, the Rams ran 13 on
29 of their 72 offensive plays, a startling 40.2% of their snaps. To put that in perspective, the
Pittsburgh Steelers lead the league with a 15.9% 13 personnel rate
for the entire season – 52 plays out of 327. Teams just don’t run 13 this much in a single game, and you would expect it the least from an 11 personnel evangelist like Sean McVay. "