Got this in the big bundle, and going to comment on the content warning a little. Now, the CW does mention altered states of sentience, and the other comments mention the CW should be taken seriously.
What's missing from it is the lack of informed consent. The protagonist is essentially tricked into said mental changes with no idea of what to expect in advance, or opportunity to decline. This, and not what was actually mentioned in the content warning, is what makes me uncomfortable with reading the story further.