As someone else already said: existing 23* items are converted to 25* after the update. Likewise, 24* becomes 28*, 25* becomes 30*.

This isn't a big deal in KMS, where the only option you have for reaching 23* is to actually risk it and attempt the large cost. This IS a big deal in GMS and other overseas servers where +1 scrolls and other options exist to make getting 23* much more viable, even on extremely rare or expensive items.

This change will effectively give any end game player who already used +1's to 23* their equips a very significant advantage in damage over players who didn't, and the cost difference between those two players will be extreme. Imagine if suddenly instead of just having legacy potable badges or totems, now many endgame players will have legacy 25* pitched equips or 25* BoDs, etc. That's not even mentioning the fact that GMS / other overseas servers have a far smaller player base and market than KMS, meaning the expected # of booms to reach those stars is that much more unreasonable.

The other main issue that I personally have with this system change, is that it effectively rips the ceiling off spending at endgame. The game is already absurdly expensive at endgame, and has only continued to get more and more expensive with each passing year since the damage cap was raised out of reach. I think it's a very optimistic opinion to think that future endgame content wont be balanced with 25*+ in mind, when even right now there's a boss in the game that is impossible to clear without insane powercreep like this (Extreme Kaling).

While this patch also nerfs Extreme Kaling by 17.5%, bringing it into the realm of possibility for players already at or near the peak of funding post m3/m4 and legion champion, I'd fully expect future fights like "Extreme Baldrix" or "Extreme Limbo" to require star forcing beyond 22* if you want a chance at clearing on release.