What is PMS5003 telling me?

Bought a PMS5003 + cable + Part. Mat. Breakout at the end of January. It is sat indoors on my windowsill, hooked up to a Pi Zero W running Raspbian.
It seems to me like the readings are a “randomised” every time I start all.py:

22:00, ~22:55 and ~23:30 was when it was restarted. I don’t understand why there is such a large difference between the readings before 22:00 and after. The fact that this happens whenever all.py is restarted suggests to me that these readings aren’t a true reflection of the environment.

Zooming out to ~30d view, all these discontinuities in the readouts are happening when all.py is restarted:

[nah, you’re not allowed two pictures in one post]

Can anyone help me interpret these data? Do I have a duff PMS5003?

30d overview:

Does anybody else have stats from their PMS5003 that they could share for comparison?