I literally just built a new workstation with 256GB of DDR5 ECC memory and had two detected bitflips within the first hour. It's likely that something's off with the timings or voltages, then, but... if I didn't have ECC, didn't have an AMD processor that generates MCEs Linux can decode, or didn't have a kernel set to log MCEs, would I know about them? Definitely not.
But because we had some equipment that would checksum itself we were able to see the bit flips happen, probably every 1-3 weeks or so I'd find a bit flip.