Was there anything happened around Jan 20, @21:30?

CPU jumped from average of 30% to 60%, bandwidth jumpe3d from average of 15mb/s to almost 40mb/s.
There wasn’t any change in my gunicorn configuration nor my application.
I ran top command and found gunicorn consumed almost 100% cpu.

  12203 chariya   20   0  822400 348132  17792 R  99.0   4.4   2:17.49 gunicorn
  12500 chariya   20   0  777204 379904  17344 R  97.3   4.8   0:45.42 gunicorn
  12518 chariya   20   0  955128 557472  17344 R  46.5   7.0   1:03.91 gunicorn
  12537 chariya   20   0  584088 186712  17344 R  45.2   2.3   0:57.25 gunicorn
  12520 chariya   20   0  501596 104076  17344 R  26.9   1.3   0:40.43 gunicorn
  12492 chariya   20   0  502640 104900  17344 S  20.6   1.3   0:37.56 gunicorn
  12485 chariya   20   0  586032 188912  17344 S   4.3   2.4   1:54.61 gunicorn
   3543 nginx     20   0  162596  25296  19636 S   1.7   0.3   4:52.36 nginx
  12206 chariya   20   0  544992 147452  17344 S   1.3   1.8   3:14.78 gunicorn