Question about the Matek WS2512b.
Does anyone know what the 4 smaller solder pads can be used for?  Dout to other LEDs? Can't find any info on this anywhere. I'm assuming they're for QA testing in the factory but maybe someone curious like me has already fingered it out.   Pic in the attachment has the pads circled.
Any info is appreciated,
Thanks

If you have a multimeter, you can put it into continuity mode and try if you find continuity between the pads and some other pads or perhaps the DOUT of the last led on the board.
I have this board and a multimeter, but since I'm currently in the middle of moving, all my stuff is packed already, so I can't try myself.

I have the same Matek WS2812B buzzer and LED board. It's on a build and not easy to get access to the pads so I can't double-check, but I did previously probe those 4 tiny pads and found that one of the pins was connected to the 5V pad and another was connected to the GND pad although I don't remember exactly which pads. The other two don't have continuity with any of the other main pads. Sadly, none appeared to be connected to DOUT so you can't daisy chain other LED boards onto this one, which means this has to be the last board in any chain.

Those pads are more than likely for programming the onboard MCU that controls the LEDs and buzzer.