It's not a serious issue at all, it's just a nuisance noise. There may be some extremely tiny minority of users where this noise actually undermines some real work, but, then so would any other equivalently powerful computer. What this is really about is expectations of Apple products set both by history and by marketing. The quality of the noise emitted is very low compared to typical Apple products, though, I'm sure one could find past examples of annoying fan noise coming from some Macs in the past.
Compared to the sound of some home built PC with similar capabilities, it's still very quiet. I'm sure I could find case fans that lack the whine, but, that's mainly because I've spent a decent amount of time building SFF machines where the fans are very exposed and put effort specifically into learning which brands are more reliable about this. That said, recently on my gaming machine one fan from bar far the most reliable "quiet" fan maker (Noctua) started to slightly rattle and I can hear it and it's taking all my self control to not order a replacement ??
I have mentioned before that I have devices with fans that exhibit exactly the same quality of noise (but louder) and they have run for 3 years of high use and they are fine, so, I don't see any reason to think this is a prelude to some actual hardware failure.
It's just very, very, very annoying (to some people) and below Apple standards comparatively speaking.