How to fix Y layer shift on Creality Ender 3?
You have a case of layer shift. Layer shifts happened to me in 3 ways:


The movement of the axis is hindered. Check if all cables run freely and without any chance to catch! improper cable chains can cause binding and stop the printhead or bed in movement and thus induce a shift.
The acceleration might be too fast. Shift the acceleration of the printer movements down a notch. Don't print faster than ~60 to keep the acceleration in check, as the printer will try to reach the top speed as fast as possible, thus limiting top speed also limits acceleration.
The model might be broken. Re-slice the model just in case.