"Specify your character set early" warning

Hey there. I've been working on optimizing my site and, using GTMetrix along the way, trying to pinpoint my issues. While I can't begin to comprehend how to fix most of them (I rely heavily on plugins and copy/pasting code others suggest,) there's one theme specific message that pops up.

In my list of results, one says "Specify Your Character Set Early" and when I click for more details, it says: The following resources have no character set specified in their HTTP headers. Specifying a character set in HTTP headers can speed up browser rendering. https://www.blindluminations.com/wp-content/themes/generatepress/fonts/generatepress.woff2

I don't think this was always there but have no idea what I could've done to create the issue. Any idea what the problem might be and how to fix it? Please take baby steps with me because for as much as I know, I'm still very much a beginner. Thanks in advance for any assistance that can be offered! :)