It's possible that my experience may not directly relate to your situation, but I encountered a similar issue with my device. Suddenly, every webpage I visited would display in a font that I found extremely unpleasant, despite being content with the default font previously. No matter how many times I changed the font settings, the unwanted font persisted. Desperate for a solution, I even resorted to downloading a font extension, only to be met with disappointment when it failed to resolve the issue.
In a last-ditch effort, I decided to reset my settings, which did successfully revert the fonts back to normal. However, this action also removed all my extensions. Upon re-enabling them one by one, I quickly discovered that the culprit behind the font problem was the Speechify extension. Once I disabled this specific extension, the fonts returned to their original state.
I share this story in the hope that it may provide some insight or assistance to others facing a similar dilemma.