Fontproblem in preview mode but displays fine in prototype view

I have a simple setup:

-A button component which is underlined on hover.

In preview mode the font is not displayed correctly. And sometimes the preview mode goes crazy and shows that the font is not loaded, even though it is a system font Arial Black. But I only have this problem with all fonts in preview mode.

Only when I load the prototype does everything work perfectly.
I find it strange that preview mode reacts so differently than prototype mode. I have this problem with all my files in preview mode, that the preview renders the font differently than the prototype mode.

Can someone help me?
I have already reset the cache program cache. But it didn’t help.

Here is the basic file:

And here are some screen-recordings of the problem: