738 Yaw Damper Flaps 30

[B-767 fan]

in the QRH of Yaw Damper light the last item is to not exceed flaps 30, i was wondering why is that and whats the relationship between them



https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/556x788/untitled_0c6dddf7d08cddb31b0a925359a5aa6477e3d921.png

[70 Mustang]

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/916x392/f1efa9d7_7dcd_4836_a64d_9fe4f45f48ac_f160c47806299a492bdea33 bccce0021cb36794c.jpeg
from another source...