I can't find variable refresh rate in macOS big sur / jittery effects/ laggy machine

my experience with Big Sur is bad so far, I hate it a lot, its so inconvenient, I have a jittery 16 inch MacBook Pro which worked perfectly with Catalina, now im having some weird problems, my Mac is so laggy/ jittery I don't know why here's my specs...

plus im not seeing variable refresh rate option in screen settings in macOS big sur why??

16 inch MacBook Pro late 2019

CPU : 2.3Ghz 8 core i9

32GB RAM

5500m 8 gb gpu

2TB SSD

please help me I can't have this all the time it drives me crazy because this Mac is my primary machine