Not what you’d prefer to wear, but what you have to:-).
For me: as casual as I can possibly manage. In the past that has varied anywhere from shorts, up to button up shirts and slacks, or down to pajama type pants (combined with maybe a nicer shirt during a Zoom call:-).
But I’ll probably have to dress up more in my next job, maybe, and I’m not really looking forward to it.:-(
Last week, I showed up to an online interview in a t-shirt. I normally try to at least throw a polo over it when I’m interviewing for a job but I was working and didn’t think about it.