Why is my Audi A3's coolant level dropping?

I noticed that the coolant level in my Audi A3 keeps dropping even though I haven't noticed any leaks. What could be causing this issue?

It's possible that there is a small leak somewhere in the cooling system that is difficult to detect. I would recommend having a mechanic check for any leaks and repair them if necessary.

Another possible cause could be a faulty radiator cap that is not maintaining proper pressure in the cooling system. You may need to replace the radiator cap to fix the issue.