Currently, the trust level method is calculating trust level based on maximum value from:
- locked trust level
- group automatic trust level
- previously granted trust level by admin
https://github.com/discourse/discourse/blob/main/lib/trust_level.rb#L33
Let's say the user belongs to groups with automatic trust level 1 and in the meantime meets all criteria to get trust level 2.
Each time, a user is removed from a group with automatic trust_level 1, they will be downgraded to trust_level 1 and promoted to trust_level 2
120a2f70a9/lib/promotion.rb (L142)
This will cause duplicated promotion messages.
Therefore, we have to check if the user meets the criteria, before downgrading.
41f78b31a9