Bugs you want to report once? A spec change? We don't know which, but we would like to see one or the other reverted. That's our guess,

[Moving on the ground]
Until 1.20.51, when dashing on the ground, the first tick was running speed.
After 1.20.60, when dashing on the ground, the first tick is walking speed.
[Movement in the air]
Until 1.20.51, 1st tick when dashing in the air is walking speed
After 1.20.60, 1st tick when dashing in the air is running speed

This means that you can no longer do various moves, and you can no longer use the same coordinates that you could use until 1.20.51.

(Coordinates means that if you do this move from this position, you can ride that gimmick.)

If this is a bug due to a fix or a spec change, either way it doesn't concern us.
If this is a spec change we are very sad and retiring from MCBE.
If we have been running 1.20.51 up until now, I don't see the point in changing it now.

Please go back to 1.20.51.
We love Minecraft and are life, parents.
Please let this voice be heard and please take immediate action.

↓Reference video.

https://1drv.ms/v/s!Att4Lmnvv_WSg0BZiBn9_8GamFUk