Anesthesiologist here: what you are referring to exists, but is rare and is not related to general anesthesia (equally likely in operations performed while patients are awake with regional anesthesia or under general anesthesia). It is more people with pre-existing cognitive dysfunction that are elderly do not handle the inflammatory milieu generated by surgery. You can Google “postoperative cognitive dysfunction” for more information.

Any phenomenon more widespread than the above is simply not supported by scientific studies to date.

I’m honestly a bit disappointed to find this comment on hacker news, as I feel the level of discourse here is usually higher. I wish you all the best and hope you recover from whatever you’re experiencing, but this is frankly fearmongering.