It would be interesting to know what the departure clearance was in regard to altitude.
Afaik altitude in Russia is not in feet but in meters below transition altitude. The first dip on the graphics looks like the pilots following an atc command like "descend to 2000m" or similar (2000m aprox. 6700ft) and then later a clearance for higher. Just a vague possibility. What's strange is that the rapid descent thereafter was absolutely straight which would suggest that the plane was at least partially under AP control.