Throttle jumps in Betaflight from 999 to 1005


The throttle (instead of stay at 1000 in Betaflight) jumps from 999 to 1005 and the drone is very restless. I checked the wiring and soldered again (if some wire is bad), but the same. What can be the problem?

what transmitter are you using?
how old is it?

Have to calibrated your ESCs?
Are your end points set correct… 1000 > 2000 when you move the stick full deflection?

I am using FS-A8S transmitter. I disconnect everything, just the transmitter is connect to the board, the same problem, like something interrupt the quad(see in Betaflight) when I change the sticks. Not smoothly movement…

fs-as8 is the receiver, you probably have slightly worn gimbles on transmitter, try setting Minimum Command (ESC value when disarmed) on Configuration page to 1010 see if that helps.
obviously make sure motors dont spin at this ESC setting first.
Also try set RC deadband to 10 in receiver tab, try this first.