Patents are intended to be the form of first public disclosure of an idea. Disclosing it before patenting it can prevent the patent application being valid.

US has a 1 year grace period. In most countries, any public disclosure makes an idea unpatentable.

https://outlierpatentattorneys.com/patent-public-disclosure

This always grinds my gears. For some people "discoveries" are so obvious, they don't bother writing a paper let alone patenting it. Then someone goes and patents it...