Rule: After message has been received → Hide tags → NonJunk
The rule is enabled and applies to all accounts. However, I tested it with a newly received message and the NonJunk tag still appears
Sounds like it’s the adaptive Junk filter causing it from either Thunderbird or another Mail client based on Thunderbird as @Olivia_Rust advised in her post below in the following thread and what you can do to remove the non junk tag.