when you're playing in the 1.12 and change to the 1.13 (any of the snapshots or pre-release) the sensitivity changes it's speed, but not it's sensitivity level.
i have my sensitivity level in 46%, i'ts going well in 1.12.x and oldest versions, but in the 1.13 it decreases the speed, so you have to change it to a superior level. and if you want to go back to the oldest version, the sensitivity level increases as you change it in the 1.13 version
Linked issues
duplicates
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Thank you for your report!
However, this issue is a Duplicate of MC-121381.
It has been linked to this report.
1.13 updated to LWJGL 3, which uses a different way of getting mouse input. Different behavior is to be expected; just change the sensitivity value in controls if you feel the need.
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