Season 1 was an incredible start, would rewatch that season again any day - and I'd do well to forget the other two. Second season had its' rough patches but was somewhat bearable through the rough writing of the story development.
However, season 3 is a flaming dumpster fire, and is more of a BDSM Nickelodeon teenage show. The writing is horrible and plain lazy at times. The characters developments have been almost been stripped down into new ones - dumber ones. Perhaps that's why it felt like the actors cared less when delivering.
Riverdale writers have infected the show - so get ready for vomit inducing dialogue such as "Daddy" and "End game".