All caps

Capitals work by breaking the pattern of the text around them, which means they stop working the moment everything is capitalised. One word in caps pulls the eye. A whole title in caps reads as noise, and it burns the character budget you need for the actual promise before the title truncates on a phone.

Uppercase is also slower to read. Without ascenders and descenders the word shapes flatten out, so a viewer scanning a feed works slightly harder for the same meaning. Thumbnail text has the same problem with less room to lose. Emphasis is a limited resource, and if everything shouts, nothing does.