Replaced struts make car drive worse?

Yup, db, I’m sure.
Compare the holes in the bushings that hold the bar to the chassis on any vehicle with some miles on it to the hole in a new bushing and you’ll find perhaps 1/8" difference in diameter. Every time a wheel goes up and down, the metal bar twists within the rubber bushing. It’s actually a surprise that more of them don’t thunk.