how many teams this year have a different design jersey to last year, let alone over say the last three years? I’d wager it’s majority of them and probably nearly all of them in three years
You can split hairs over what a different design is, but:
Canberra - have changed their "home" jersey but retained last season's as a heritage which they appear to be wearing regularly.
Canterbury - same design since 2013, and their general design hasn't changed for 45-50 years save for the bowing of the chevrons and whether they're cut by a sponsor.
Cronulla - varying themes on the same hoops for at least a decade now.
Newcastle - have stuck with the classic Henny Penny look for a good 5 years now haven't they?
Parramatta - also seem to have settled on the 80's-90's style as their main kit
Penrith - similarly have settled into the black with three colour band
St Geo Illa - duh
Souths - duh
Roosters - duh
Warriors - now 3 seasons in with the 95 strip and judging by the away, looks to be keeping that style
Wests Tigers - same basic design concept for a good 5-6 years now as well.
Broncos, Titans, Cowboys, Melbourne do seem to shift their designs around fair bit, probably because they're younger clubs I guess. Manly seems to be having an identity crisis too, which is odd because their jerseys have been good for the most part in recent decades.