This has already been discussed somewhat at https://community.openstreetmap.org/t/post-hidden-by-community-flags/3367. There, someone linked to https://meta.discourse.org/t/what-happens-when-you-flag-a-post/275 which essentially said “how flagging works may be changed by the people administering a particular site”.
Depending on the trust level of the user performing the flagging, I suspect that that that is possible, and the trust level needed to do that isn’t actually that high. See also https://meta.discourse.org/t/trust-level-permissions-table-inc-moderator-roles/224824. That table suggests that TL1 (anyone who registered 24 hours ago) can do this, but just to be clear again, those appear to be defaults. and may be different here.