Mine came from https://www.geewiz.co.za/ups/124927-acconet-poe-48v-24v-smar... Looks like this may be a South African domestic brand though (and you probably don't want to order from a South African site unless you're living in the country to be honest).

If it's just PoE you're looking for there are other options available - e.g. https://www.amazon.com/Battery-Uninterruptible-Security-1000...

One thing to be wary about though is max power if you're trying to run a raspberry pi with hard drive attached off one of these devices. A lot of these devices cap output on the USB ports at ~5V/2A (which I think was the USB2 max whereas USB3 allows for more). If you're running off an SD-card or SSD you should be fine, but 2A isn't enough to start a pi from an attached 2.5" HDD in my experience.

A cursory search of AliExpress found these potentially interesting candidates:

https://aliexpress.com/item/1005003164049579.html, https://aliexpress.com/item/1005004107179526.html (POE)

https://aliexpress.com/item/32964061367.html (wall wart style)

https://aliexpress.com/item/1005003765804094.html (looks like a power bank with always-on output like the article is describing)

https://aliexpress.com/item/4001204992959.html (BYO 18650s and enclosure)

https://aliexpress.com/item/32421259702.html (looks interesting but sadly "dead", was cached in google search results from however long ago)

Similar-ish PoE UPS for $55 USD, https://www.amazon.com/Battery-Uninterruptible-Security-1000...