It seems we have some limit to how large banner we will display. ssh itself seems to be capable of displaying much more.
Should work fine now.
I could reproduce this bug with 4.11 client against 4.11 server on RHEL 7. Tested nightly build 6513 containing the fix and it works fine. Relnotes also looks fine.
(In reply to Niko Lehto from comment #4) Tested the client on Fedora 31.