Switching labs in grad school is not uncommon
If the university you chose does not have a rotation system, you are left to pick a lab based on your interest in the research and with a general idea of how the PI will be as a mentor based on the quick interactions you have had.
If your university does have rotations, you gain a general understanding of the lab environment and the mentor-student dynamic.
Unfortunately, your time in the lab may not always pan out the way you hoped it would.
It could be that:
the mentorship style is not the right match for you
competitiveness in the lab is toxic
there is no work-life balance
you are no longer interested in the research you’re doing
mental health or life events
no structure or support