@Ziggy
The site is https://chateaugallery.com. I added some text on the homepage for an exhibition and the font sizes shrank. Everything is still an H1, H2, etc. but the text is the same size across the site. I'm using the stock font set from Squarespace to my knowledge.
"Helvetica Neue."
The text size shrank and the glitch unformatted the entire site after a basic edit.
Edit: I reset the font pack and it looks like it's working, hopefully.