Hi, when I was trying to crate some horizontal subplot, I had an unexpected x-tick in one of the plots. I re-created that with an mre for the first subplot and the sin-curve form the subplot example, ...

According to doc of ultraplot.subplots (or ultraplot.Figure), there are four levels of axis sharing. 0 or False: No axis sharing. This also sets the default spanx and spany values to False. 1 or ...