I don’t know about iPads, but my iPhone shows a message when the delayed charge thing is active. I think it’s even one of those always on notifications you can’t swipe away.

Delayed charge (waiting to charge fully or charging the last ~20% slowly to just-in-time for your alarm) is a different setting, though I don't recall the name for the "Only charge to 80%" one

"battery saver"

Can you tell an iPhone to only charge to 80%? I only have the “optimized charging” option, which is the delayed one.

Yes.

> To change your charging option with iPhone 15 models and later, go to Settings > Battery > Charging and choose an option. You can choose a charge limit between 80 percent and 100 percent in 5 percent increments.

https://support.apple.com/en-us/108055

OK, that explains it, mine is an older model. Wonder why this setting doesn't apply to them...

Probably a combination of the devices being old enough and the battery not being large enough that a lot of people would not find 80% of the already-degraded capacity of their device reasonable, and not wanting to have to explain to customers why their friend’s phone allows it and theirs doesn’t if they both have the same model.

Yeah, USB-C is a bit of a nightmare when it comes to knowing what a given cable can actually do.

Well, all cables can charge at least. It is not a usb-c problem but an apple and /or charger manufacturer one.

My bet would be sth about the voltage the charger provides.

Its not the setting. It charges fine to 100% with the same wall-wart and a tiny usb-a to usb-c adapter then the apple cable. But not happy with my regular usb-a to usb-c cable (that works fine with everything else). Or any of the other cables in my house. A message pops up about non-compatible cable. I suspect the ipad has been designed to be deliberately fussy. I'm in europe, if that makes any difference.