Google Lighthouse flags the pages that do not have the necessary font size (font size smaller than 12 px):
In Lighthouse’s audit, if more than 60 percent of a page is smaller than 12px, the page is marked. If the ratio is not that high, the audit is passed. But we still recommend that you check and optimize this page.
On the result page, you are presented with the source, selector, percentage size of the problem in text and font. You are expected to analyze the problem based on these variables.
How to pass the audit? – Fixing eligible fonts
Check font sizes via CSS. If the error in the Lighthouse report says ” Text is illegible because of a missing viewport config ”, what you need to do is adding between the <head> tag of the document ” <meta name = "viewport" content = "width = device-width, initial-scale = 1 is to add ``> ”.