Flexibly Stratified Comprehension is inconsistent. By Flexibly Stratified Comprehension, there is an s such that
∀x(xεs<-->∃y(∀t(tεy<-->tεx))∧y∉x). If sεs$$\forall x\:\bigl(x\in s\leftrightarrow\exists y\:\bigl(\forall t\:(t\in y\leftrightarrow t\in x)\land y\notin x\bigr)\bigr).$$ If $s\in s$, then there is an S$S$ with the same members as s$s$ such that S∉s$S\notin s$.
But if S∉s$S\notin s$, then for all T$T$ with the same members as S$S$, TεS$T\in S$. In particular SεS snd$S\in S$ and thus Sεs$S\in s$.
If s∉s$s\notin s$, then for all S$S$ with the same members as s$s$, Sεs$S\in s$. In particular sεs$s\in s$.