Forerunner 955 HR sensor problems

Hello , Ihave been experiencing an issue with my FR 955 lately. The wrist heart rate shows some crazy values. On the graph, you can see the heart rate during walking. The drop from 130-140 BPM to normal value (60-65) happens a second after restarting. Has anyone had such a problem? Is it a fault of the new 22.22 software? I marked the moment in red when I turned the watch off and on again