Scene moving bodies are slower after just launched

Phaser 3
1

Continuing the discussion from Is it possible to make graphics physical:

Sometimes when a scene first starts or tab switched, if it has moving bodies they move slower than they are meant to. Also sometimes the opposite happens. the bodies get slower. Like in this video taken:
phaser-demo1.m4v (1.4 MB)

I have seen it in:

  • here
  • Phaser your first game tutorial I have built reading along. the player, dude, runs slower at the beginning of the game. Available here on Phaser labs:

None of these examples have any code that programs them to behave in this way.
I will try to collect more examples.

What can be the reason of that? Is that normal? Anybody else experiencing the same issue? How to fix that?

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