Many, several ages back, there was a Multiverse warfare where every deadline battled for supremacy, inducing the Timekeepers to look and then rearrange all of the timelines into a single. : sacred deadline. Now, if somebody does something out this most important deadline’s strategy – that is as insignificant as being late for work or as big as negotiating a Tesseract block – that a brand new branch is made, making a “event”. Nexus”. If this is not discovered and controlled, it could create more and more forks, leading to a frenzy and the potential of another Multiverse war. Because of that, TVA is created and anyone outside the main timeline (called ‘variants’) will be kept and that timeline will be wiped out.
Through that, the MCU explains why the time-lapse “thieving” does not actually mess up the deadline as you initially believed, as it is an occasion that needs to occur, but the escape Loki is from that program. Given all this, Doctor Strange’s coming mad Multiverse may have its origins in’Loki’ or’Spider-Man: No Way Home’, hence creating a much bigger event than’Spider-Man: No Way Home’. Avengers: Endgame’.