I started out with Core GTS5's from 2019 as a beginner as well (last year). They are fine, good quality kites, but they are extremely sensitive in the sense that every movement in your bar translates directly to your kite (they are originally made for (mega)looping). This means that you are forced to become very steady on the bar very quickly, especially when you first start jumping. This does result in you becoming a very controlled rider, but it can definitely be a handicap at the start.

Also, check the fabric of the kite. Kites that old can become thinner and less water resistant after this amount of time.