I have had arrays with greens, blues, reds, red pros, golds and shucked from usb whites all mixed, some red 2.0 some are 3.0
I have swapped them about in a few different configurations over the years.
I still have a 2tb that works and I’ve just ordered 2 14tbs
I’ve only ever lost 1 drive and it was under warranty and that was probably my fault (it might have been shaken a few times on a wobbly table)
The amount of drives it’s rated for is mainly vibration (AS FAR AS I WAS AWARE ANYWAY)
but just you can mix. (You should be able to mix by brand / size / class / interface / speed / technology as long as the software stack can handle it.
I use unraid and synology so I’m not limited to 1 drive size per array.
You might have to match sizes for your array but that is a software thing.