I mean
She literally had a tech on the device days before.
He serviced the freezer side fan.
If he scraped the evap and caused a tiny leak, that could very well have caused a potentially explosive mixture to form in the freezer.
Unfortunately, in this case, the leak was probably INSIDE the fridge, with very little air exchange to the outside.
Much more likely to form an explosive mixture under these circumstances.
It is true that R134a is much less volatile.
But much more environmentally damaging.
Going back a couple decades, the very first fridges used pure ammonia. Exploding fridges weren't terribly uncommon in these days.
But thinking further:
R290 has been in use in heat pump tumble dryers for a few years now, as well as fridges over here.
And I have yet to hear of any explosion regarding a fridge, freezer or dryer.
I guess it is very much a case of "If it works it works, if it dosen't it REALLY dosen't."