Verified with 4.4.0-0.nightly-2020-07-08-233114 and the issue has been fixed.
The "alpn h2" has been removed from the backend.
server pod:caddy-rc-f29lg:service-secure:10.128.2.15:8443 10.128.2.15:8443 cookie 900d6e0b534db276ba867eb8faf4d2fb weight 256 ssl verify required ca-file /var/lib/haproxy/router/cacerts/hongli:myreen.pem check inter 5000ms
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.