Make a right working STL export Feature Please!

[Rosketch]

As in The Year 2015, SU 2020 hast a wrong working STL export Feature: it changes Surfaces to the Bad Side,when One mirrored objects. Same Problem as in 2015. In 2016 to 2018 the Problem was solved, Now it is back again.
Reported by Rosketch.

[Box]

This really isn't a feature request, it's a bug report.
Here is a visual of what Rosketch is talking about.
Two components in SU, the right one has been flipped along the red.
When exported as an .stl the resulting file is unprintable, as shown here in red.

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