Infrared

1. Общност
2. Technical Issues and Workarounds
3. Nice Streak Badge

Yup, I received the badge. You can also earn It multiple times!

1. Общност
2. Technical Issues and Workarounds
3. 50 badges showing as retired.

Same here.

1. Общност
2. Feature Requests and General Site Feedback
3. Streak system

There used to be a streak feature but they removed it at the beginning of 2021. I really want streaks and the clockwork badges back.

1. Общност
2. Technical Issues and Workarounds
3. 50 badges showing as retired.

I would like to see helen keller, millionaire, ramanujan, 299,792,458 m/s back. 

1. Общност
2. General Khan Academy Questions
3. black hole badges

I don't even know if it is available. Even if it was, I would not bother trying to get it.