Sometimes, big tech companies move real fast, and sometimes, they move real slow, and Apple is guilty of moving at a particularly glacial speed with a fresh change that's debuted on the MacBook Air M4.

The new mute key, complete with revolutionary strikethrough symbol (Image Credit: MacRumors)
MacRumors noticed that the icon on the mute key of the MBA M4 is now a speaker symbol with a strikethrough line running over it, to indicate in a traditional fashion that it cuts the sound.
Previously, on Mac keyboards since the 1999 PowerBook G3, the symbol for mute has simply been a speaker icon - with no line through it.
As MacRumors points out, technically that isn't incorrect as such, because the function key can be used to mute, or unmute, the sound, and so the old design of the symbol fits in the latter case.
However, most people think of the key for muting, not unmuting, naturally. And because it's positioned right next to the volume down function key, which is not that much different to the old mute design - just with a tiny added curve symbol next to it - these buttons were easy to mix up for some.
Meaning that some folks ended up muting the sound, instead of turning down the volume.
Some people certainly argue that there wasn't much of a point of confusion here, but still, it was an oddity with the keyboard, and a slight pitfall for some Mac owners.
Whatever the case, it's now gone, and the Magic Keyboard with the iPad Air has the same mute design, too. So, we can expect it to be the new design going forward with all Apple's Macs, no doubt.