Hard pass, that's essentially unusable.
How you handle it is project-dependent. But if you're doing a real web site, not an SPA, you can show an error/help page, or re-load the current page with the error/help message.
FWIW I find the native date picker to also still be quite poorly performing in practice, despite quite robust browser support. I wish it worked better but for many reasons, I still see plenty of users (or bots?) who submit dates in the wrong format for whatever reason. My current hypothesis is largely focused on password managers though since they will often do whatever they want directly in the value attribute of an input element.