Are you sure you’re definitely forcing the Temporal AA, and setting anti-alising quality to “epic” level, and not overriding those config values during runtime or with custom scalability profiles?
Also try disabling Screen-space reflections to determine if it is the issue I’m thinking about.
if this definitely doesn’t help, please fill the bug report if not sent already, be ready to make a reproducible mini bugged project for proof for the dev team, or they won’t start fixing ever.