As well as the 2 answers above you can also try re calibarating the joy con and lastly reset the console by holding down the power button for 10-12 seconds. Usually the 4 things mentioned here combined will sort it out. Changed about 5 sets so far and no issues now
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EDIT Sorry didn’t fully read your question seems you did calibarate it already. So it could be the housing around the joystick has become dislodged. You cant also rule out that the replacement stick is just faulty. Usually in those kits you get 2 or 3 sticks so try another.
As well as the 2 answers above you can also try re calibarating the joy con and lastly reset the console by holding down the power button for 10-12 seconds. Usually the 4 things mentioned here combined will sort it out. Changed about 5 sets so far and no issues now