Hmmmm….. That’s funny I don’t see that happening unless you are adding a Sub-D modifier to the curve perhaps? (P.S. it looks terrible out of the gate with sub-D applied on basic text converted to curves)
If you need crisper resolution you can change the Render U Resolution between bezier vertices. And the bevel resolution will adjust the resolution of the cross section (unless you add in a bevel object then it’s own Render U resolution should set that up if I understand it correctly).
But again, not saying you have to use this way. I just love using curves whenever I can now haha.