Altitude fluctuating about 10m in auto mode

My plane is about 5.5kg, wingspan 1.8m.Firmware 3.5
As below

Altitude used to maintain well,about 1m waving.
But now,i don’t know when,the altitude fluctuating more obviously,10m maybe.
Altitude below i set was 100m.

It flies well in FBWA mode, maintain the airspeed well, hit the flight course well.
And i try to do the TECS tuning ,including adjusting TRIM_ARSPD_CM,TRIM_THROTTLE, TECS_TIME_CONST.But without apparent improving.
Log is a little big,you can download it below.
Hoping you guys can help me fix the problem,I was completely depressed by it.

anybody know? Hoping your reply:sob: