I think you are misremembering. Chrome won at the start because it was fast as fuck and Firefox was not. Firefox caught back up in the 2016 time frame iirc and they’ve been back and forth ever since.
Ironically chrome was named so as a goal was to reduce the chrome of the UI and focus on the web content, something recent versions of chrome and Firefox have abandoned in favor of massive swaths of whitespace and giant chrome buttons (on Firefox you can enable “unsupported” compact mode to reclaim some of the space if you’re on a laptop)