Yep, I know exactly why! You had a normal pavlovian brain response, albeit a semi-extreme one. (Having had long covid 3x and still recovering from the last one years ago it's very justified though imo...) Your brain negatively associated the idea of being around people with getting you sick and harming you. So just recovering from covid, and knowing that it was caused by being around people, is a huge source of subconsious anxiety. It's an aerosolized virus, so everyone talking is just them spraying their virons into the air for you to then breath and get you sick AGAIN.
Just like eating a food that makes you feel like crap especially if it makes you throw up. It is disgusting/repulsive to your body after that experience because your body associates it with sickness.
You mellowing out is called the mere exposure effect. Basically you got re-exposed to the same stimulus (human contact) without the negative effect (getting sick).
This retrains your brain to unassociate the negativity and move back towards positivity.
The same technique (exposure therapy) is how anyone can get over basically any phobia, some people with extreme phobias just need a slow/steady introduction. e.g. fear of elevators. You just get as close to being inside the elevator as you can initially. Sometimes this is just being across the room and looking at it at first. Once you become more comfortable with that you get closer to the elevator, maybe you push the call button and watch the doors open but you don't get in. Then maybe you put one foot in the threshold then pull it out. etc. etc. Next thing you know you are using the elevator like normal with no fear/anxiety about it! :)
