Yes it’s bylaw 11 of standard bylaws
11. Cleaning windows, etc
An owner or occupier must clean all glass in windows and doors on the boundaries of the lot, even though they may be common property.
But the problem is the Strata have painted the window such that they will not open and that is a Strata problem to fix and once fixed the lot owners are liable to clean the windows from the inside (providing it safe to do so).