Well, for example, everyone was playing with toys when they were little but they don't anymore because they had to be someone else to survive due to how society is even though we are still a child in our heart who want to play with toys.
In the context of "desperate times call for desperate measures" we adapt therefore we do different actions even though we ain't fundamentally changed. A personality never changes but the behavior does so people behave differently depending on what the situation requires them to do.
Behavior also depends on the DNAs you activate which are triggered depending on what kind of situation you are in. These activated DNAs don't change personality but it changes how this personality behaves as if putting a rock on the river (personality) or removing the rock from the river so the river flows in a different way but the river itself fundamentally doesn't change. That's how it's in your brain.
So for example, a workaholic INFJ can turn into an ISTJ to finish the work before the deadline. Any personality in the business world will start to act like ENTJ and whatnot to keep their job. Though this latter situation is more about mirroring which what we humans do sometimes to be in synch with the other for a common goal. It can be explained by how your memory affects your behavior. For example, so many people behave like a kid when they are around their parents but they behave like an adult around some strangers.
The brain is rather interesting about how it can change its "task modes". For example, a woman starts "mother mode" when they are with their kid but when they work they start their "work mode" so these different modes make the person behave differently but still the personality doesn't change.
You gotta consider the mind as a building, personality is the foundation of the building, behavior is the first floor, 2nd floor is memories that affect the behavior, 3rd floor is personal preferences, and so on. So, in buildings the items inside of them can change but the foundation doesn't change. It's the same for people.
MBTI ain't about personality but it's about behavior so yeah people's MBTI type changes of course.
