Quad strain help

As the weather’s just got bad again in the UK I’m back on the trainer and have noticed something odd. When on the trainer my vastus medialis (just above knee and inside) on my left leg feels mega pumped and is limiting my workout. I’m using the same bike as I ride outside so I assume fit isn’t the issue? Has anyone had any experience with this before?

Also an unrelated q, is it possible to set and indoor and outdoor ftp for outdoor workouts? My indoor ftp is about 10% lower than outdoors

No, there is only one FTP in TR.