Something wrong with trust graph

First time user of Tribler. I added 5 torrents that I have already downloaded full with another client. I stopped Tribler and copied the data in the download directory, restarted Tribler and forced recheck of the data for the 5 torrents. From that moment on I was only seeding for a day now.

With 7.4.4 I was actually seeding quite a bit and seing many peers (resulting in negative credit, see other discussion).
With 7.5.0-rc1 I do not see any peers anymore and I am not seeding, so something seems broken in 7.5.0-rc1.

Furthermore: in both 7.4.4 and 7.5.0-rc1 is sporadically see the trust statistics produce a graph like this:

I now see so many issues that I do not even know where to begin using this software. It seems unusable / broken. Please help me see how I can actually use this tool.

Thanks for the detailed report!
Tribler underwent a major Core refactoring for version 7.5, so some bugs are expected. Also, the development team is really small at the moment, but we are actively hiring now.

Having said all that, could you please repeat your report on GitHub directly? When you report there, your issue is more likely to get resolved.