From a FAQ answer here on Meta (emphasis mine):
When an account is suspended
[...] The user page will have a visual reminder that the account is in timed suspension. It will also include a brief summary explaining the reason for the suspension.
- Note that the public "reason" shown for the suspension is based on the moderator message template that the suspending moderator decides to use, so that reason may not necessarily correspond to the actual reason the account was suspended. In particular, if the moderator decides to start from a blank template, it will show as "for rule violations", so seeing that reason doesn't necessarily mean that the user has violated a specific, codified rule.
Would it be possible to fix these templates so that the wrong reason is not displayed? Documenting "the displayed reason is wrong" in a FAQ instead of fixing the issue seems bad practice.
A comment by a SE moderator @Glorfindel on Meta.MO suggests instead that the reasons are accurate and the FAQ is wrong; I am not able to check this because I don't have the power to suspend anyone. In that case, of course, it's the documentation that should be fixed.