This happens when I try to move with the mouse any articulation of force under a slur.
Yes, I believe this was brought up here in 2020. Once again Leo had a workaround.
Is it better if you use the Alt Up/Down arrows?
This works reliably for me, inasmuch as the slur stays outside the accent, if that’s what you have requested by specifying that the Position of accent and marcato relative to slurs engraving option is set to Inside slurs. But dragging an accent will not position it outside the slur: Dorico will move the slur to remain outside the accent.