If you miss shifts in a restaurant, you're gonna be fired. If a sales rep frequently has to cancel meetings with clients that's a problem. And if you're in middle management you've got a lot of meetings that can't be missed.
But software development is pretty forgiving, and even more so now with remote work. A lot less meetings, a lot more people working highly flexible hours.
As long as you can deliver a full time job's worth of productivity over the course of a quarter, if health concerns make your productivity much more variable so that you've got slower days and faster days, slower weeks and faster weeks -- and that your faster periods compensate for the slower ones -- you'll probably be OK. At least the places I've worked.
If your health problems and pain are such that you can't deliver a full time job's worth of productivity, or where you expect to be frequently missing whole weeks or months due to health issues, then of course that's another story.