I still have the small Ubiquity switch with PoE (60W) and it only seems to have 802.3af. The AP doesn't work with it, although it should support the standard according to the website.
So I think my APs can only support the proprietary 24V, which is also stated on the enclosed injecters....

The UAP AC Lite now support 802.3af - i.e. 48V active PoE. The manufacturer's website also says so (https://www.ui.com/unifi...). Unfortunately, they did not do this from the beginning, so the versions up to about 2017 only supported passive PoE.

If you still have the old ones, you can simply replace the switch with a USW-8-150 - it can also support passive PoE. However, since the price for this is also just under 200.- (https://www.digitec.ch/de/s1/product/ubiquiti-us-8-150w-10-switch-5776956), the question is justified as to whether you should simply buy newer AC Lite UAPs.
By the way, you can recognise the newer UAP Lite by their packaging - they have a blue triangle with the note that they now also support 802.3af.

You can also read the documentation on compatibility here: https://community.ui.com/questions...

Regarding your original question; if the five-pack does not have a thick layer of dust, active PoE should already be supported. 😉