Any web designer who doesn't, in 2021, understand and make allowances for 4k/5k ultra wide monitors as well as phone sizes screens in portrait mode - isn't doing their job right.

The problem here is not the monitor shape or the user's browser window width, it's the css (and maybe html) and the lack of understanding of how to use it properly (or, more sympathetically, perhaps a conscious choice on the part of the people paying for the website to not allocate enough budget to cover all their competent webdev's suggestion?)