Your question is a good one. I'm not the one who downvoted you fyi. To answer your question, it is absolutely a personal anecdote based on my own experimentation. I'm sure others will add their own experiences. Based on my experiences there's no doubt about twitch shadowbanning based on VPN use. I'll admit I don't have a basis for Linux and adblockers being a part of the equation, but I made it clear in my original post that those were assumptions.
To further speculate, I have an idea that the shadowban may actually be triggered by somebody using the same VPN server doing something that triggers it, affecting anybody else on that server. I can't possibly provide evidence for that theory, but it would explain the seemingly random nature of the shadowbans.
It's trivial for twitch to differentiate between users who are logged in and have verified accounts. Slapping bans by IP is archaic and lazy when you have more precise metrics to go by. And at the very least, they should make you aware that you are banned before accepting your money for their services.