In LOITER sudden altitude changes

I’m currently flying with vers 3.4.6.
Its a 4s copter with M8N gps, LIDAR LW20 and IRLock over I2C

When my copter stays in LOITER from time to time the copter suddenly changes altitude eg. from 12m down to about 7m
Can someone figure out why this happens?

My interpretation:
It looks like some wrong values from the LIDAR were causing this… Is the I2C failing?

HERE ist the log file: