My windows 10 taskbar icon width is so wide
Update I've found out how to switch this off!
- Go to Settings (e.g. [Win]+I), then System, then Tablet; or hit [Win] and type "Tablet settings" to go straight there.
- Click "Change additional tablet settings"
- Under "When I'm not in tablet mode", set "Make app icons on the taskbar easier to touch" to off
Original answer
Are you using a 2-in-1 PC in "tent" mode (maybe with an external keyboard and mouse)?
According to WinCentral, It appears this is a new "feature" in version 2004 (aka 20H1) for 2-in-1 PCs to make it easier to use the touch screen when not using as a "normal" laptop.
I'm afraid I've not found out how to turn it off yet, but it's REALLY annoying!
The only work-around that I can find is to flip your laptop over and use it as a conventional laptop - the icons return to normal size.