For exported projects, you can have a problem with basic fonts.
Some of the fonts on Tilda come from the font libraries by
type.today service that provide these fonts under a partnership agreement:
For these fonts and other built-in fonts to display correctly on your exported website, you need to add the domain you are exporting your website to in the Site Settings → Domain. It is enough to specify the name of the domain, you do not need to connect it.