The Red Hat Enterprise Linux Application Streams Life Cycle document's "RHEL 9 Full Life Application Streams Release Life Cycle" section does not list Redis 6.

Because Redis 6 is provided as a plain RPM through the Application Stream repository:

  # dnf list redis
  {...}
  redis.x86_64    6.2.17-1.el9_5    rhel-9-for-x86_64-appstream-rpms

...as well as a newer major version as a module:

  # dnf module list --all redis
  {...}
  Name     Stream    Profiles      Summary
  redis    7         common [d]    Redis persistent key-value database
  Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled

...the version 6 should be listed in that document as being supported through the whole 10 year life of RHEL 9.