I’ve noticed recently that I seem to get more engine braking than I remember my bike having. It’s not noticeable if I free wheel, so it must be something engine related.
Try some Redex (or similar product) as it available in most petrol stations. Could make a difference and its only a 5er a bottle. Remember that the dose stated on the bottle is for a 60L car tank and not a 13-18L motorcycle tank! Just under a quarter of a bottle will be sufficient for your bike.