Most likely the infamous needle bearing in the front differential. There is a T-SB on that (T-SB-0012-19). The noise should go away when you drive in 4WD.
See
2020 4R needle bearing
Edit: T-SB-0012-19 is for '16 4Runners and up.
T-SB-0026-15 is for '04 to '17 4Runners.