It is not a Gravit Designer limitation or any settings. The SVG format contains a piece of font information and when this font isn't available it replaces the font with another one.
If you are creating a design using, for example, a web font, when you open this SVG and this web font is not actually installed on your machine (Gravit Designer doesn't install fonts from the web, it shows you the fonts so you can use them, but you have to install in order to see them outside Gravit Designer) you will notice a replacement.
The same thing would happen if you import a font on Gravit Designer, create an SVG and send it to another person (who doesn't have the font installed).
In order to avoid that, before exporting your design, please select your font and go: Modify > Path > Convert to Path (make a backup before doing that) and it will convert your font into paths, avoiding font replacement.
If you are using the Advanced export (ctrl+shift+e) you can also check the "export text as curves" option - https://share.getcloudapp.com/Apuk0PEL