This is a really weird thing and I can't get consistent results - even using 2 hands to make sure it's not timing. For the most part on my systems it does not RTZ with a quick double tap on the spacebar and when it does it seems like an anomaly.
When I saw the reply saying it was a shortcut to RTZ, I tried again on a new project and it was working!?
...but now it doesn't again even after trying different projects and a reboot. idk