When you want to include a font from Google Fonts it suggests ([1]) you do it like this:
<link rel="preconnect" href="https://fonts.googleapis.com">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Roboto&display=swap">
The preconnect to fonts.gstatic.com makes sense since the browser will otherwise only find out about that domain after it has downloaded the stylesheet. But what's the point of the preconnect to fonts.googleapis.com when the link to the stylesheet is right after it? Won't the browser process both of those at the same time?
[1] See: https://fonts.google.com/share?selection.family=Roboto, select some style and and click briefcase icon in the upper-right corner.)
By preconnecting with https://fonts.googleapis.com, the webpage is optimizing the loading of the font stylesheet itself. As Google documents:
The performance bump is likely negligible since the stylesheet itself is usually tiny, so I'm not sure why this is included by default. However, it does still technically do something. I'd suggest removing it, as it makes no difference in load times.