In the early days there were quite a lot of bugs that affected Chrome and not Firefox from what I recall. The problem was Chrome didn't run on Linux or Mac in the first versions, but Google engineers (by policy) didn't run Windows, they almost all ran Linux. So there was a huge testing gap. On the other hand it was helped by the fact that Chrome was basically Safari at that time so Mac users within the firm tended to notice bugs during dogfood/canary periods.

I can't quite recall the timelines, but I remember it felt like years before the Chrome team shipped a native Mac/Linux version. They also fixed a lot of bugs that broke features of the various apps, e.g. lack of printing was a big one for a while.

I imagine you're talking about later when Chrome got really big. But it's hard for me to say what would have happened because when the features are themselves being developed in Chrome there are hardly ever cases like that when it works in every browser except Chrome and this is somehow not noticed during the canary period.