I've also hit this problem now. I have a cluster with two members.
02 was built a while ago at R81.10, upgraded to R81.20, then R82, now R82.10.
01 originally followed the same path. I tried to roll it back to a snapshot I took manually on R82 so others on the team could run the upgrade, but the snapshot is broken. A very large file (snap_log_backup.tgz) was added to /tmp while the snapshot was being taken, and it prevented other, more important files from being copied. I've confirmed this happened on both members, and I've got a ticket about it.
I just restored 01 factory defaults on R81.10, used config_system to run the first-time config, updated CPUSE, upgraded to R82.10 (via 'installer upgrade'), installed the sk184766 hotfix, established SIC, and pushed policy. Once it was talking to the management, I tried to get it to the same config as 02 (except IPs, hostname, and other expected differences). I can't because 01 has these options and 02 doesn't.
SomeFirewall-01> set ssh server kex [Tab]
curve25519-sha256
curve25519-sha256@libssh.org
diffie-hellman-group1-sha1
diffie-hellman-group14-sha1
diffie-hellman-group14-sha256
diffie-hellman-group16-sha512
diffie-hellman-group18-sha512
diffie-hellman-group-exchange-sha1
diffie-hellman-group-exchange-sha256
ecdh-sha2-nistp256
ecdh-sha2-nistp384
ecdh-sha2-nistp521
sntrup761x25519-sha512@openssh.com
SomeFirewall-01> set ssh server mac [Tab]
hmac-md5
hmac-md5-96
hmac-md5-96-etm@openssh.com
hmac-md5-etm@openssh.com
hmac-sha1
hmac-sha1-96
hmac-sha1-96-etm@openssh.com
hmac-sha1-etm@openssh.com
hmac-sha2-256
hmac-sha2-256-etm@openssh.com
hmac-sha2-512
hmac-sha2-512-etm@openssh.com
umac-64-etm@openssh.com
umac-64@openssh.com
umac-128-etm@openssh.com
umac-128@openssh.com
SomeFirewall-01> set ssh server public-key [Tab]
ecdsa-sha2-nistp256
ecdsa-sha2-nistp256-cert-v01@openssh.com
ecdsa-sha2-nistp384
ecdsa-sha2-nistp384-cert-v01@openssh.com
ecdsa-sha2-nistp521
ecdsa-sha2-nistp521-cert-v01@openssh.com
rsa-sha2-256
rsa-sha2-256-cert-v01@openssh.com
rsa-sha2-512
rsa-sha2-512-cert-v01@openssh.com
sk-ecdsa-sha2-nistp256-cert-v01@openssh.com
sk-ecdsa-sha2-nistp256@openssh.com
sk-ssh-ed25519-cert-v01@openssh.com
sk-ssh-ed25519@openssh.com
ssh-dss
ssh-dss-cert-v01@openssh.com
ssh-ed25519
ssh-ed25519-cert-v01@openssh.com
ssh-rsa
ssh-rsa-cert-v01@openssh.com
And on member 02:
SomeFirewall-02> set ssh server kex [Tab]
curve25519-sha256
curve25519-sha256@libssh.org
diffie-hellman-group1-sha1
diffie-hellman-group14-sha1
diffie-hellman-group14-sha256
diffie-hellman-group16-sha512
diffie-hellman-group18-sha512
diffie-hellman-group-exchange-sha1
diffie-hellman-group-exchange-sha256
ecdh-sha2-nistp256
ecdh-sha2-nistp384
ecdh-sha2-nistp521
SomeFirewall-02> set ssh server mac [Tab]
hmac-md5-96-etm@openssh.com
hmac-md5-etm@openssh.com
hmac-sha1
hmac-sha1-96-etm@openssh.com
hmac-sha1-etm@openssh.com
hmac-sha2-256
hmac-sha2-256-etm@openssh.com
hmac-sha2-512
hmac-sha2-512-etm@openssh.com
umac-64-etm@openssh.com
umac-64@openssh.com
umac-128-etm@openssh.com
umac-128@openssh.com
SomeFirewall-02> set ssh server public-key [Tab]
ecdsa-sha2-nistp256
ecdsa-sha2-nistp256-cert-v01@openssh.com
ecdsa-sha2-nistp384
ecdsa-sha2-nistp384-cert-v01@openssh.com
ecdsa-sha2-nistp521
ecdsa-sha2-nistp521-cert-v01@openssh.com
rsa-sha2-256
rsa-sha2-256-cert-v01@openssh.com
rsa-sha2-512
rsa-sha2-512-cert-v01@openssh.com
ssh-dss
ssh-dss-cert-v01@openssh.com
ssh-ed25519
ssh-ed25519-cert-v01@openssh.com
ssh-rsa
ssh-rsa-cert-v01@openssh.com