It's not the first time that a person takes a liking to a development board or module and after some time, months or years, buys it again and finds that the product behaves completely differently from the hundreds bought before.
This happened to Petr Stehlik, a popular youtuber and blogger. He bought a new batch of DC-DC step-down converters with the MP2315 chip and found out on an expensive device that it didn't work as it should. And the 60 USD device doesn't work anymore either.

Petr wrote about the working step-down converter on his blog and video: http://joysfera.blogspot.com/2018/09/novy-maly-usporny-uzasny-dc-dc-step.html (czech language)

As it is the case with Chinese manufacturers, in an effort to save even a penny, they replace a tested chip with a (often unsuccessful) clone. Of course, nobody bothers to test the whole module and so it goes out into the world.
Petr Stehlík not only lost his 60 USD device, but also his favourite module. What now?
He tweeted that he will design his own - so we have something to look forward to!

And how to recognize a fake module? At first glance, they are indistinguishable from each other. But the second time, with a magnifying glass in your hand, you can tell.
The original chip is marked AGCx, the fake one DKAAD. Which, of course, is subject to change. What's more bad news, you have to buy the module to find out what it's fitted with.

Zlá novinka: číňan zkriplil další step-down! https://t.co/DnLkEouCzu jsem používal 5 let. Nadšeně jsem o něm i blogoval: https://t.co/n4GHJhgZTM Teď jsem koupil dalších 20 ks a když mi pod rukama shořela zařízení za 1500 Kč, zpozorněl jsem. Už tam není MP2315, ale nějaký aušus! pic.twitter.com/bBafraekFr

— Petr Stehlík (@joysfera) November 30, 2022

ten s AGCx je ještě pravděpodobně ten dobrý (~MP2315), ty strašné "klony" mají označení DKAAD

— Petr Stehlík (@joysfera) December 1, 2022