Sometimes you may detach a server from its ipv4 and you have ipv6 only connectivity. (for example I had to downgrade MySQL version, so I switched the ipv4 to a backup instance to move the traffic away)
In that case you cannot install packages via apt because repo.percona.com resolves to ipv4 only:
E: Failed to fetch http://repo.percona.com/ps-80/apt/pool/main/p/percona-server/percona-server-common_8.0.22-13-1.focal_amd64.deb Could not connect to repo.percona.com:80 (167.71.73.251), connection timed out