Probably the biggest let down of an ending of any manga I've ever read. Plenty of other manga have ended in ways that pissed me off, this ending just straight up bummed me out. Its just so obvious that Ishida gave up around two thirds of the way into Re and didn't end it the way even he wanted to.
The original TG and first two thirds of Re were almost perfect manga. The art was amazing, it was incredibly well written and you could tell that he was trying to build up to an amazing and unpredictable ending. Sadly, around chapters 130-140 of Re, everything takes a massive nosedive and its extremely noticeable. Art gets worse, dialogue gets worse, writing becomes contrived and weak, then we get this bullshit shonen like ending with very little meaning at all. Its a real bummer. I really believe that this isn't the ending Ishida wanted to write, but judging by his interviews and his letter to fans after the ending this was all he could muster.
You can go read the letter and interviews yourself and draw your own opinions (I think they are still somewhere on the TG subreddit), but basically what I gathered is that Ishida was so obsessed with this series for the seven years he was writing it that it eventually took over his life and made him start to lose his mind. Judging by some of the things he said, it was really affecting his mental health in a bad way and though he tried to couch it, it really seems like his obsession with the manga ended up forcing him to basically give up on it. Its pretty obvious when you reread Re, everything is so methodical until about 40 chapters from the end. Then he just gives up and we get a shonen battle manga for the last 40 chapters with mediocre art.
So who is to blame? Do you blame the manga industry for only caring about money and forcing writers of extremely popular manga to work tirelessly until they are empty enough to give up on their own beloved series? Or do you blame the mangaka, who willingly hand full control over their IP to these greedy companies without a second thought just so they can make their money? Honestly I'm not really sure. All I know is this toxic industry has ruined so many good manga, and I have real respect for mangaka and publishers that allow long hiatuses to give artists the time they need to give their story a real ending. I would rather TG be delayed for months at a time like Berserk and still be good, than get this crap ending. What I really wish is that manga were written from beginning to end and then published, like novels in the western world. We would probably get much stories that way. Probably a lost cause to hope for that though.