I bought one of these inexpensive MB102-style breadboard power supplies (Elegoo brand) and the output voltage I measure is incorrect. It is supposed to be 5 V but it is only 4.24 V.
I thought it might be defective so I bought a second one made by a different manufacturer and it also does not produce 5 V. Instead, it produces 4.46 V.
In both cases the 3.3 V output voltage is correct.
So is this problem with the 5 V output voltage then typical of these MB102-style units? Is it an issue with the design perhaps, or just bad build quality? Or maybe it's because ~4.3 volts is often considered "good enough"?