Started having some weird FPS drops whenever I back to base. AFAIK it's only in ranked too

A couple days ago my game started doing this weird thing in ranked where whenever I back to base my FPS drops to 40 or 39. It doesn't fluctuate or go up or down or anything, it's like it's just FPS capped at 40 frames. I can fix it by changing my graphics settings from very high to high OR high to very high, or any other graphics setting, up or down. It pretty much only happens in ranked from what I've seen, not sure why. My PC has always been able to run League on high settings just fine, normally getting ~180 FPS. Once I fix it by changing graphics settings it runs completely fine until the next time I back into base. I've never had this problem before and I don't know what's causing it. I tried updating all my drivers and doing a full repair in the League client, but it's still happening. I looked it up online and I can't find anyone else who's had this problem or any other way to fix random FPS drops. Let me know if you've ever had this issue or can think of a way to fix it; it's very annoying.