Bitcoin Core supports running onion service and recently added i2p. I want to understand the trade-offs in using different combinations of networks, so asked a question in Bitcoin SE earlier: https://bitcoin.stackexchange.com/questions/107060/tor-and-i2p-tradeoffs-in-bitcoin-core
1.1 Tor only 1.2 i2p only 2.1 Tor + ipv4/ipv6 2.2 i2p + ipv4/ipv6 3.1 Tor + i2p + ipv4/ipv6 3.2 Tor + i2p
Unfortunately nobody answered it yet and doesn't look like many are interested based on discussions about it. I think its very important for a user to understand the difference between Tor only and Tor with other networks in Bitcoin Core in terms of privacy and security.
Things that I read already but didn't help much: