Maximal orthogonal grassmannians of quadratic forms of dimensions up to $22$.

Let $X$ be a connected component of the maximal orthogonal grassmannian of a generic $n$-dimensional quadratic form $q$ with trivial Clifford invariant. Consider the canonical epimorphism $\phi$ from the Chow ring of $X$ to the associated graded ring of the coniveau filtration on the Grothendieck ring of $X$. In \cite{Kar2018} Karpenko proved that $\phi$ is an isomorphism for all $n\leq 12$ (conjecturally for all $n$). Recently, in \cite{Yagita} Yagita showed that $\phi$ is not an isomorphism for $n=17, 18$. In the present paper, together with Yagita's results for $n=17,18$, we show that the map $\phi$ is not an isomorphism for all $13\leq n\leq 22$. In particualr, the case $n=13$ gives the smallest dimensional maximal orthogonal grassmannian whose two graded rings are not isomorphic.