Torn rear hub

You’re right, I’m sure.
Btw, did you check the spoke’s tensions at the front wheel?

Re: My Strida SD (Sport Duo)

Broken spokes

Another broken spoke on back wheel

Once again, I’ve checked ten (10) original Strida wheels (three 18" wheelsets and two 16" wheelsets) -

ALL of them had (more or less) loose spokes…

Slutty built wheels over years?

If you mean original Strida wheels you’re right, but

It should be said officially that the most durable combination has to be that of a 16" rim, 36 spokes and an 18" hub.
(Optimal spoke pattern has to be discussed…)
A disadvantage of 18" wheels might also be the small amount of fitting tyres.