1. Login as a Channel Member who does not has access to use Channel Mentions.
2. When the channel member uses one of the channel mentions like `@all` or `@here` and sends a post, the channel mention does not gets highlighted.
3. However if a sysadmin sends a post on the same channel containing a channel mention like `@all` or `@here`, all the previous posts of the Channel Member also highlights the channel mentions.
Please check this GIF to demonstrate this issue:
Expected: The channel mentions highlighting should not change