Bo Nix dropped back to pass 641 times as a rookie. He threw the ball 567 times, was sacked 24 times and scrambled 50 times. His 50 scrambles were the third most in the NFL behind only Jayden Daniels (73) and Caleb Williams (51). Fellow rookie Drake Maye (45) also scrambled quite a bit considering that he played much less than the other rookie QBs.
Rookie QBs tend to scramble for two reasons, they tend to get blitzed more often than veterans and that can result in them running, they also have less familiarity with their WRs so most of those scrambles end up as runs instead of big play throws like you might see from Josh Allen or Patrick Mahomes.