If the user enables the grid, and then disables it in Desktop view, when they switch to Sketch view, the grid will be shown. This reversed logic remains in place for the remainder of the session. (enabling the grid and switching will no longer show it)
As a follow-up, I had used the edit-grid tool previously, not sure but this might be related...starting Gemini up afresh and I'm not getting the behaviour - I'll watch more closely and see if I can replicate more easily.
I'm sorry, we had to drop support for the sketch and gemini variants of Krita because with the existing code, we couldn't make it work with Qt 5.