I have started to measure my consumption using Shelly devices. I have installed two Pro 3EM in the electrical distribution board. This represents the complete power consumption. I have also installed 10 Shelly Plug S Plus. These are the main consumers.
So far, everything looks “plausible”. However, some characteristic curves of the current line show a strange course. Does this also occur with other loads? It seems to be particularly noticeable with low consumption, but also with consumers that draw significantly more power.
Power factor is a factor 
Your 3EM’s are for sure more accurate 
Accuracy class B (active energy)
Shelly Pro 3EM-3CT63 has a
measurement accuracy of 1%.
then your shelly plugs that only feature a HLW8012 for power measuring 
If you seek more accuracy (or smoother graphs) I suggest installing esphome on your shelly’s and set the update_interval to 0.5s or less. That way more “real” values come in and less filtering (like average/throttle) happens which causes the graphs you see now 
Thx. I will check this out.