What causes words to appear in different fonts within the same DOM element?

Question

HTML

Sometimes I catch a strange bug on my project (wordpress site): within the same DOM element (most often this is the title), sometimes different words and even symbols are displayed in different fonts. At the same time, it is impossible to intentionally reproduce the bug: it sometimes disappears on its own, sometimes it appears. It was such that the bug disappeared even without refreshing the page. One time it disappeared right before my eyes when I opened the Chrome Web Developer Tools (F12) -- i.e. everything became the same font, as it should be.
All fonts seem to be loaded from Google Fonts. At the same time, in the theme (a theme from another developer), it seems that several fonts are connected, separated by commas, but we only need one.
Does anyone know what could be causing this issue and how to fix it? And then some magic happens ...

Answer 1

Here you can already see that the download of the font seems to be canceled