Any idea why there's so much dust?

if you have forced air heat A/C you might need you duct work cleaned then a decent filter

Your duct work may need cleaning out.

Same thing at my house but I live in a hot dusty climate next to interstate 5 and insist on the windows being open when possible.

Try wet dusting, replace all hvac filters and or see if your ducts need cleaning. Typically a tight system will not need this, but worth checking. See if this helps!

https://www.goodhousekeeping.com/home/cleaning/tips/a2429/dust-causes-may02/

https://m.wikihow.com/Reduce-Dust-in-Your-House

https://molekule.com/blog/where-doest-dust-come-from-source-house-solutions/

Do you have a window nearby? Sunlight produces dust....keep the shades closed and you should have significantly less dust.

Do you have dry skin? 90% of dust in dead skin particles...creepy, but true.

check your furnace filter

I'm guessing it is because you are dry dusting, or your vacuum cleaner is spitting dust out. Dusting with a damp cloth helps a lot. Don't forget that pillows, cushions, mats, comforters and draperies hold dust too. Stick them in the dryer to loosen things up a bit.