Is it normal to shower with underwear on?
Depends.It depends
Yes, some people shower in their underwear, often for modesty or comfort. It’s a personal preference, though underwear may not rinse or wash as well as it would in the laundry.
Sure. Some people keep their underwear on because they feel more comfortable or modest, especially in shared bathrooms. Others just prefer showering nude. There’s no one “normal” way to do it.
If you’re wearing underwear in the shower, it’s best not to treat that as a substitute for washing it in the laundry. Wet fabric can also feel clingy and take longer to dry, so do what feels comfortable to you.