When you reach the end of a level, you get a Level Complete screen, that shows a bunch of statistics, and asks you if you want to save the game or not. Runners found a new way to skip this, by pressing alt+f4 then pressing no when reaching a Level Complete screen.
This alt+f4 method is from now on NOT allowed for Glitchless runs. Instead, you must go through Level Complete screens by pressing ENTER twice then pressing "No" to the "Would you like to save?" question (or "Yes", if you like to be slow).
Here's a comparison showing both ways of doing it: Example on the right is the one you shouldn't do. Example on the left is the right way to do it.
This is an update, for anyone coming from the Glitchless Ruleset. Back Handspring Zipping has been determined similar to Left Roll Zipping, making it not allowed to perform during Glitchless runs from now on. If you want an example of what is now allowed and not allowed in terms of back handsprings, here's a video: Examples 1 to 3 show back handsprings that are now not allowed anymore. Examples 4 to 8 show back handsprings that still remain allowed.