Health app reduce my step

I sync step from garmin and once app health show around 22,xxx at time around "00.1x". And I get back in app health again after midnight around 00.30. I saw that app health drop my step count from 22,xxx turn to 20,687.

So you will see from photo that in garmin connect count step is "21,963" (it should be the base minimum) so once i saw in app health is more than "21,963" but after that app health drop my count.

Not drop my step count only this day. But It's about 2-3 times and I don't know why.

Thx for the answer in advance.