The thing is in cultural it's not the case that students are held to their admissions statement interests. In this case, it's exactly that, a POI who wanted a protege to take on his personal work. Any deviation from that, even minor ones, would not have been acceptable. What's especially disconcerting about this was that the POI never even hinted at this in initial discussions and went through 10 days of emailing about (every day) about research areas before finally being pushed to reveal that this would be the case.
There are a host of other reasons I'd label it toxic, based on not only this but also the fact that students are finding it impossible to finish because of too many new admits, not enough TA spots for funding in the years after the funding runs out, difficultly getting access and support from supervisor and from committee and from department, etc. I looked at the graduate student association meeting minutes going back years and every year they brought up the same problems over and over, and the department hasn't addressed them.
Also, when I reached out to the department, the faculty member in charge of the grad admissions process literally said "I haven't been doing this long" so couldn't answer my questions about how funding works - but also couldn't direct me to anyone who could. The department took days to reply to simple queries, and generally felt distant and reluctant to help me find answers to questions about the offer they were giving me.
Finally, the real sign was that of all the dozens of current students I reached out to contact about life in the department - only 2 replied. At every other school, all of the students replied, usually with glowing recommendations. In this case one was somewhat positive and one was negative - but only two even bothered to reply.
Edit: I should add this was the exact opposite in all regards of the other programs that made me offers. One of the scariest parts was the one student who did have positive reviews of the department said "it's great except for difficulty getting time with your supervisor, competition with other students for funding, x, y, z, etc." listing all these horrible things that aren't the case in some programs - but which this student said they assumed was normal in programs! I'm glad to have had a lot of experience (~5 years) working closely at a PhD only university with faculty and students and knowing how it ought to be!