<span> or <small>
I used a <small>© 2019 Hedgehog Headquarters</small> instead of <span>.
In a previous video he said its ok to use it, as long as it's with short text. Plus i remember seeing this used elsewhere. But also if span is used to select in CSS, i'm thinking we could easily give <small> an id or class to reference in CSS.
And i don't believe its such a problem, it does validate.
<span> doesn't change anything but <small> changes some things.