This is common with many bikes for as long as I can remember (30+ years). It’s not an issue that you have to do anything about, it just means your not shifting correctly. On bikes you don’t do ‘the car’ shift on these (Off throttle, disengage clutch, shift, engage clutch while adding throttle).
You just have to preload the shift. The trick is to apply pressure to your shifter (like if you are going to shift, but not quite), and hold it, then off throttle while pulling in clutch and the pressure you’ve already applied to shifter should allow it to slip into next gear with no clunk. Thats the proper way (and cooler way

) to shift.
For down shifting, you don’t have to do anything special, but if you're clunking, it just means your down shifting too early, if you let rpms come down more it shouldn’t clunk.