Support for EAPI=8 was recently added to font.eclass (see bug 806496), but this is not reflected in the devmanual: https://devmanual.gentoo.org/eclass-reference/font.eclass/index.html
Eclass documentation in the devmanual is automatically generated from app-doc/eclass-manpages. We make a new snapshot a few times per year, but not after every eclass update. Current version is 20220316 (and it just missed the font.eclass update), so it may take a couple of months until the next version bump.
I'll make a new snapshot as soon as the updates currently under review in gentoo-dev have been merged (i.e. vim-*.eclass and elisp-common.eclass).
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=692c36871773850f3b9341939200ba95cdb8c61e commit 692c36871773850f3b9341939200ba95cdb8c61e Author: Ulrich Müller <ulm@gentoo.org> AuthorDate: 2022-04-17 20:31:45 +0000 Commit: Ulrich Müller <ulm@gentoo.org> CommitDate: 2022-04-17 20:34:30 +0000 app-doc/eclass-manpages: New snapshot 20220417 Closes: https://bugs.gentoo.org/836902 Signed-off-by: Ulrich Müller <ulm@gentoo.org> app-doc/eclass-manpages/Manifest | 1 + .../eclass-manpages/eclass-manpages-20220417.ebuild | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+)