Time warping in orbit around a celestial body at any scale may lead to random decrease or increase in speed.

[Genekermanisamoneylaundere]

I discovered this bug after trying to rendezvous in an apollo style mission and my ship kept randomly changing speed every time I timewarped whether it be 2x or 100x, I got a random increase or decrease in speed. For my craft, it was always around 40 m/s for both the lander and the transfer module.