Good tips above.
I had the same issue.
RTX 4080, 13600KF, 144Hz Freesync monitor
FG + DLSS caused lots of tearing for me, TAA seems to fix the issue, but only if set at 100%, or just turn off AA .
I also capped my frame rate to 120 in NCP, which is more than enough for MSFS, and prevents excessive frame rates in the menus.