Why are there multiple methods for moving the finger during tashahhud?

Why are 2 method of moving up our finger in swalaat? Some lift their finger up and then put in down. But some repeatedly lift it up and down till swalaat end

There are more than two methods. The reason is that we have many hadiths on this issue and they contain conflicting accounts of how the Prophet PBUH moved his fingers during the tashahhud. Different scholars preferred different narrations, so they came up with different views of how it should be done.