I’ve encountered this several times in the past few years too, usually in the form of sites acting bizarrely or functions not working in Safari and/or Firefox. There’s been some active useragent sniffing too, though ironically enough in those situations it’s usually enough to spoof the user agent after which the sites in question as far as I can tell work properly.

Either way it gives the impression to non-technical users that non-Chromium browsers are subpar even if site devs are to blame (especially when “upgrade your browser” messaging is misused to equate your up-to-date Safari/Firefox with some derelict version that hasn’t been updated for years) and will only serve to strengthen Chrome’s hold. The only recourse Mozilla and Apple have are to perfectly emulate Chrome’s behavior and in the case of UA sniffing even pretend to be Chrome, which sounds an awful lot like the bad old days of Gecko needing to emulate IE to make sites work in Firefox.