Hi! I'm wondering what kinds of issues Gimbal Lock results in, and how we can use quaternion to fix them ~ also are there any other ways to solve it?

I found a Youtube video with a good visualization here, at 1:30 it shows what weird result it could lead to, and at 3:00 it reveals the root cause. Essentially it's because two or more axis are rotated into a same direction, and subsequent rotation on different axis will start to affect each other, hence formed a "Lock"

I think the physical-world version of this caused some problems in the old Apollo space program: https://www.hq.nasa.gov/alsj/gimbals.html