Two pages I look at every day had the same problem: monospace text that was too thin and pale to read comfortably. One was the log viewer in our Airflow 2.7 web UI, the other the dark theme of an internal Tabler dashboard. In both, Chrome was drawing the text in Courier New, a hairline font, even though both pages list four or five better fonts before it.

The cause was a fontconfig file from the fonts-powerline package, installed in 2019. It puts the symbols-only “PowerlineSymbols” font in front of most monospace families, and Chrome then refuses every one of them. A one-rule fontconfig file fixed it.