> It’s especially common in vertical videos like YouTube Shorts, where the stored resolution is a square 1080 × 1080, and the aspect ratio makes it a portrait.

My guess is this is because encoding hardware can do max 1920x1080, and there is no easy way to make that hardware encode 1080x1920, so you are forced to encode as 1080x1080. Swapping rows and columns in hardware tends to be a big change because caches and readahead totally changes when you process the data in a different order.

They've supported 4K for so long that I'd be surprised if they don't have enough boards capable of 1920 height.

And even then, why make it 1080 wide?

I feel like there's more going on. And maybe it's related to shorts supporting any aspect ratio up to 1:1.

But that's all assuming the article is giving an accurate picture of things in the first place. I went and pulled up the max resolutions for three random shorts: 576x1024, 1080x1920, 1080x1920. The latter two also have 608x1080 options.