Money supply increased significantly in 2020 for sure but that's NOT what you're seeing in the M1 graph. M1 was revised to include savings accounts at the same time and this is the major source of the discontinuity:

https://fredblog.stlouisfed.org/2021/05/savings-are-now-more...

M2 captures the pandemic influx better and is significantly less dramatic: https://fred.stlouisfed.org/series/WM2NS