Minecraft effect?

I played Minecraft some time ago, and after starting it had a visual effect that everything that was moving, as well as dropped objects, could be seen in a white rectangle. This was very practical in dark conditions in caves to find monsters. Unfortunately, this effect is gone and I wanted to know how to get it back?

If you are currently playing in your world, then press F3 and then B. It may be that the hit boxes are displayed because you accidentally pressed something.

Thanks for the tip, it worked👍

Supi ^^