Ask for the serial number and put it into Trailhead. It will be Debonair, but that isn't a fixed specification. 2019 is different to 2021, but not necessarily better, depending on who you ask.
I think it was the 2021 revision to the airpring that makes the most difference but it is cheap and easy to changeover to the new one as a DIY job ...so not a deal breaker.
The 2021 version of the airspring resolved the perennial issue of having to balance the pos and neg air chambers during set up, and also stopped the annoying habit of RS forks sagging about 10mm just under their weight before you even set the sag. The difference that makes is that the full range of the fork is available and it is easier to get a plush initial part of the stroke.
19 model will have charger 2.0 damper.
20 model will have charger 2.1 damper and ultra low friction SKF seals added.
21 model will have the addition of the C3 air spring which as mentioned above is different but not necessarily better.
The 2019 Lyrik RC2 is still a great fork. Get it, fit the new SKF seals when it is due for a service. You're not missing much.