Firefox out of the box indeed does not cause broken websites. However, the demographic of this forum probably will use Firefox with "Multi-Account Containers", "Temporary Containers", "uBlock Origin", and a few more. These are amazing for privacy and productivity, but will occasionally cause broken websites.
Source: I am a Firefox-first user who occasionally uses plugin-less Chrome because the aforementioned plugins (and "ClearURLs", "Consent-o-matic", and a few others) occasionally break websites.
Source: I am a Firefox-first user who occasionally uses plugin-less Chrome because the aforementioned plugins (and "ClearURLs", "Consent-o-matic", and a few others) occasionally break websites.