Yep. If you write
``` © <?=$currentYear?> Your Name ```
As many sites do, it may actually invalidate your copyright. You have to put all of the years when you made copyrightable edits to the page. A range like 2010-2025 is only allowed if every single year in that range is included.
This sounds like pseudolegal folklore (in the US at least). Do you have any actual examples where this affected a case?
In the US, you get copyright on your work automatically, with or without a label.
The only thing a label does in the US is defend against "innocent infringement" defenses. But even that defense doesn't absolve the other party from liability; you just can't recover as much.
There is no reason you can't have `(C) 200X-$currentYear Acme Inc` or whatever.