I was under the impression that pyxattr is shipped in one of the CentOS 8 components? So why should it be part of epel then?

which package provide it? I can't find anything.

FEDORA-EPEL-2020-0b3ac00899 has been submitted as an update to Fedora EPEL 8. https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2020-0b3ac00899

FEDORA-EPEL-2020-0b3ac00899 has been pushed to the Fedora EPEL 8 testing repository.

You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2020-0b3ac00899

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

FEDORA-EPEL-2020-0b3ac00899 has been pushed to the Fedora EPEL 8 stable repository.
If problem still persists, please make note of it in this bug report.

Dan was correct, in RHEL and CentOS the pyxattr package has a python3-pyxattr subpackage.

# repoquery --quiet --info python3-pyxattr
Name         : python3-pyxattr
Version      : 0.5.3
Release      : 18.el8
Architecture : x86_64
Size         : 36 k
Source       : pyxattr-0.5.3-18.el8.src.rpm
Repository   : codeready-builder
Summary      : Extended attributes library wrapper for Python 3
URL          : http://pyxattr.k1024.org/
License      : LGPLv2+
Description  : Python extension module wrapper for libattr. It allows to query, list,
             : add and remove extended attributes from files and directories.
             : 
             : Python 3 version.

I've filed bug 1833571 to retire this from EPEL to comply with policy.