Vector graphics and unwanted tessellation.

My beloved graphics software recently started to produce fragmented vector graphics output.
Exported visualizations in eps files became literally uneditable using external software and files also grew in size.
It seems to be started after they upgraded their graphics engine to OpenGL
- patches appear as rectangles and lines are arbitrary fragmented (leftmost image).

note: the elements are shifted using vector graphics editor to show the composition of image
After some research in totally new field I suspect that feature called tessellation is responsible for (mildly saying) destroying the vector image.

Could it be that tessellation introduced with OpenGL responsible for this?
Is it possible to switch off tessellation (?) in applications to achieve something like on the middle and right picture?

It seems to me that your problem is with what these exports “eps files” contain. Unless the application is using transform feedback to read vertices back to the CPU, it’s highly unlikely that OpenGL has anything to do with the contents of the files it generates. And if it does, then you’ll have to take it up with the people who write this software.