Searched. Bug seems to be extremely similar to MCPE-31021 and MCPE-31024.
The top textures of stained glass pane blocks do not appear to align correctly to the pixel grid, which makes for some ugly texture messes when the panes connect up to others. Regular glass panes are not affected by this, allowing for an easy comparison.
Mark as duplicate of MCPE-31752, as this is a pretty broad glitch.