MarkObjects unload time keeps growing!

We have some games running in a theme park under heavy usage. After every run, the scene does a reload of itself to reset the gamestate.
Everytime the scene reloads, the “MarkObjects” inside the output_log shows that the unload time keeps growing after every run!
Profiling inside the editor sadly leads to no result…

The loaded objects in each scene reload stay the same, so it cannot be traced directly to scene objects.
The high unload times causes the application to get out of sync of the control software at a certain point, leading to unacceptable results.

Does anyone know what the most likely reason is that “MarkObjects” keeps on growing?

[86737-output-log.zip|86737]

Any solution to this issue ? Encounter same behaviour on Unity 2018.3

Thank you