If I think of square checkboxes I think of sharp corners. Maybe I should write an article "In Loving Memory of sharp corners" because I definitely miss them but they seem to be extinct from the modern Web and GUI in general.
If I skim the article only old screenshots contain sharp corners. None of the new once.
I have a browser where I configured "border-radius: 0 !importent" as userContent.css for fun. Was sometimes surprised how much it is used. Especially how many circles are today actually boxes with a large border radius.
> Especially how many circles are today actually boxes with a large border radius.
HTML is all about rectangles. If you want circles, your choices are a straightforward CSS border-radius, or an SVG <circle>. And let me tell you, if you can just slap style="border-radius:50%;overflow:hidden" onto an <img>, or faff around with <svg>, <image>, <clipPath> and <circle> (or maybe you can even use clip-path="circle() fill-box" these days, can’t remember if support is there yet), I know which a sensible person will prefer.
I have a browser where I configured "border-radius: 0 !importent" as userContent.css for fun. Was sometimes surprised how much it is used. Especially how many circles are today actually boxes with a large border radius.