Related to what I said above, there are stories where time travelers change the past but it gets covered up so the future doesn't actually change, stories where the past is changed and the future is radically changed (and the time traveler either ceases to exist, loses the ability to go home, or returns home to see a completely different world), stories where the past is changed but only in a minor way that only the main characters are aware or, or even stories where even the slightest change immediately fractures the timeline so any changes you make don't actually alter your own future at all, but create an entirely new world (and travel back to the future either takes you back to your original timeline, fast-forwards you on the new timeline, or becomes impossible because you can no longer access your original timeline by going "forward" - you'd essentially have to travel back to your point of divergence and then double back down the "right" timeline).
Time travel physics can get confusing. And since they're all mostly hypothetical anyway, they tend to differ across different stories, and most of the details get handwaved away as not being all that important.
The Mandela effect is just the result of time traveler shenanigans.
ParanoidObsessive posted...
It also raises the question of whether or not having ALL SIX STONES in our universe destroyed simultaneously has a much more significant side-effect than anything we see. Though that might be a moot point since Doctor Strange went on to break all of time and space anyway.
What would have happened if they used the last stones to create new stones for the present?