> it was fixed in cgroups v2

I would say it was changed in cgroups v2.

Cgroups v1 was written by a company where only one process on a machine is allowed to do block I/O, and that program is carefully written to not use kernel caches.

Cgroups v2 was written by a company that uses lots of off-the-shelf Linux applications that do ordinary block I/O in the usual naïve way. That's why v2 focuses so much on "pressure".