"Hate" is a strong word, but I very much dislike it when a website that I can access on my computer only allows phone users to actually use it, or when certain features of a website are hidden for desktop users but available for phone users, such as Instagram Stories. I just don't agree with desktop/laptop users being restricted or offered the barebones version of a website considering that the internet has existed long before smartphones were a thing.
And vice versa: sites that will render fine on a PC, but refuse to load on mobile and direct you to an app instead, or have fewer features than the full site available.
Or vice versa. Why can't I access features in the phone version of my banking site, but I can in the desktop version on my phone? Now why, if you have two versions, can I not even access both from my phone or computer?
The aspect ratio! With some hard work and intensive empathy training I got over the vertical format being default, but when someone uploads a horizontal video to a vertical format site, and then you're trying to bring it to full screen on your also horizontal monitor... I could headbutt the monitor in.
I counted pixels once. It took up less than 10% of the display area. Just a fucking thick black (EDIT: or non-video regardless) "border" on 90+% of the monitor. And why?
Because of one dipshit deciding they will consider horizontal screens nonexistent (while it's closer to natural, human vision). I can't even blame the uploader, sometimes they don't even know this use case isn't even handled.
I'm with you on the one about Instagram. I'm a hobbyist photographer trying to maintain a decent portfolio and it grinds my gears that in order to publish a collab post for example, I have to do it from the app on my phone.