Every board is connected from Trello to Placker via token, which is assigned to one of the members.
This means that if the member is removed from the Trello board, the token needs to be assigned to another member. Also, mirrored comments assigned to a member that doesn’t have a Placker account (and therefore didn’t authorize Placker to publish comments under their name) will be assigned to the member with the Trello token - learn more about this in this article.
To set the sync token to another member, please access Placker.com / Click the board title / Trello / Change sync member: