I'm seeing a number of peers (again a Russia issue) claiming 100% file availability. As the source is under my control exclusively and no upload has happened (yet), this 100% claim is 100% wrong.
What are the consequences for other clients trying to connect and download?
In case that should impact honest users: is there a way to automatically identify and blocks those instances?

You should expect that any torrent announced to the public DHT will be scraped by bots. Because it's public. There are well known sites, and those are quite useful in certain cases. To prevent that, don't use public torrents or switch to new protocol (limited to other Tixati users).

Bots from 31.200.249.0/24 subnet have been running for quite some time, but those are not the only ones that exist. They are just the most noticeable because of aggressive connection attempts. You also don't know who really owns the project, and to whom the collected data gets resold (I expect that there is more than one customer).