Im using Tor for that.

I've only ever used IRC to find ebooks and never worried about a VPN. Check #ebooks on IRChighway or Undernet.

I have been raw dogging epubs from Zlibrary, Annas, and libgen for years on public WiFi, student housing, work internet, my internet the most, but you name it.

Should I not do that? Though I'm not distributing which is usually what they give a shot about

I found everything I looked for in anna's archive so far. Since it's a simple file download I'd say it's save as long as law enforcement isn't already monitoring your connection. If that's the case you got already bigger problems.

I use a VPN and a private DNS . i feel like thats plenty and I dont have any DNS leaks from my tests. I wouldn't really trust mozzilla VPN a whole bunch but its probably fine. A real VPN provider is cheap, I'd get one. Ivpn or icevpn are good.

I've never used a vpn for libgen but I understand the need to feel safe and that depends on your threat model. What are the realistic consequences of not using a vpn with libgen for you and does using a vpn mitigate them?

I'm not understanding the risk, are you downloading at work or on a school network? is the book content illegal where you live? worried about malware maybe?

safe from whom/what is what i'm asking

You should do whatever it takes to feel safe. But FYI, no private individual has ever been sued for downloading books.

Generally downloading files is pretty much safe and untraceable. At least in the countries I know of, so this might depend on where you life. What is a problem is uploading or sharing with a torrent client. Then you need a VPN.

If you are concert that the eBooks will exploit your eBook reader and infect your device you can use a website view them like this https://epubreader.net/. They will have to escape the browser sandbox to infect you'r device witch is extremely difficult and generally don't happen if you keep Firefox updated and you are not "valuable" target.

I would disable file thumbnails in your file manger.

MAM+VPN is a good way

probably better to use it on a burner device(cheap device) if you that paranoid, and on a public wifi like library or cafes.

It strongly depends on your threat model.