Per subject:  Is it (still) true that Tixati only encrypts the ‘headers’ of the data packets, not the contents or payload, when you enable Encrypted Only connections?

Quote: (Some clients) may encrypt data ‘header’ not full stream:
Each torrent client (Vuze, uTorrent, Tixati, etc.) chooses it’s own encryption implementation. And some only encrypt the ‘headers’ of the data packets, not the contents or payload. This makes it trivially easy to identify torrent traffic by inspecting the message payload. Some clients like uTorrent and Vuze do offer full stream encryption.

1. When connecting with an unencrypted SOCKS5 proxy this shouldn't be a real problem, right? My IP will be protected. So my anonymity is safe. Or will this allow ISPs to throttle / block my torrent traffic? Or will this open me up to a 'man in the middle' attack?
And should I enable at the very least Encryption Only connections? And loose out on speed? While ISPs supposedly still can detect my torrent traffic (https://www.vpnuniversity.com/bittorrent/torrent-encryption)?  And is this why a VPN connection is advised besides an unsecured SOCKS5 proxy?

So... To summarize...

1.) if your ISP doesn't throttle torrent traffic...
Unencrypted SOCKS5 proxy will hide your IP. If you trust there'll be no 'man in the middle' attack, this will be your fastest option with reasonable privacy (= a hidden IP address).

2.) if your ISP throttles torrent traffic...
*** use Tixati's connection encryption implementation: with a little luck your ISP will be blind to your torrent traffic, if not...
*** don't use Tixati's encryption implementation. Instead, use a VPN connection to fully hide your torrent traffic from your ISP.

The first option is less secure, but you should be safe enough. Your IP will be hidden by SOCKS5. Your network speeds should be reasonably fast.

The second option offers full security (the VPN will hide your IP, it will also encrypt your traffic), but will be slower and not all VPNs are created equal: especially UDP connections will be tricky.
That's why it's smart to combine the best of both worlds. Use an unencrypted connection using an unencrypted SOCKS5 proxy over a VPN connection that allows for torrent traffic (and UDP). Your torrent client will show your SOCKS5 IP address. And the VPN connection will encrypt any traffic going through it.

Just use I2P, no need to think about using SOCKS proxies or VPN's.

Why are you reading some junk text (human-generated or AI-generated, doesn't matter) that only exists to serve ads? I know why: corporations, in the end, make money out of someone's illiteracy, that's why search results are full of junk like that.
https://en.wikipedia.org/wiki/BitTorrent_protocol_encryption
Look at the dates. You are talking about something that is long gone. Header encryption specifically has been irrelevant for about 20 years.

What is your exact problem? If you want to evade bittorrent traffic throttling, there isn't much you can do except tunnelling to an external host (e. g. using VPN). Modern DPIs can use statistical data to guess protocols, so encryption won't help, and the ISP probably simply designates all traffic which is not known good & important (e. g. biggest services) as low priority garbage, with exponential throttling based on bandwidth. And, obviously, with public torrents, everyone who can see incoming connections from peers you can't control instantly knows you have a torrent client.

If you want to cloak your real address from companies that collect them for various reasons, but can't demand to uncover client's identity globally (from ISPs in other countries), you also have to use tunnelling to an external host.

Therefore, the solution is obvious, and is readily available from thousands of companies.