Do you have examples? I use Safari and don’t find this to be true. Given Safari is what people use in iOS, id expect this to be rarely the case (most sites will test on an iPhone).
"transparent 0" is not a standard way of defining things, and bad use o CSS in production.
I don't have any proof but my suspicion is that I've seen more sites failing Safari since Mojave.
I really dislike (& distrust!) using Chrome now, especially for e-commerce sites or anything with SMS based 2FA as Safari's ability to pull codes automatically from messages is a godsend.
[1] https://stackoverflow.com/questions/35583503/input-type-sear...
Chrome also frequently attempts to cover up incorrect code with what it thinks the author probably meant. Firefox tends to be much better than Chrome at following the actual spec.
I tend to develop primarily with Chrome first for some different reasons (ability to disable CORS, support for self-signed certs with WebSockets, and its better debugging of WS frames), but I always make sure to test later with Firefox and Safari, and occasionally find code that worked in Chrome, but doesn't elsewhere, and the reason is almost invariably always that Chrome didn't follow the spec.
[1] https://developer.apple.com/design/human-interface-guideline...