Strange split of Planarsrf with ClosedPolySrf

Its one of those days where errors pop-up for no reason.
Can anyone exlpain why that happens?
The split parts look like 3d but are planar.

problem_r6.3dm (81.2 KB)

Hello- the problem is here:

Please see - Understanding Tolerances [McNeel Wiki]


Thanks @pascal for pointing where that comes from.
To be honest I don’t know how this tolerance changed as in all of my models i use Large Objects - milimeters. Therefore i would never have thought of checking that.