Responsibles are asked to approve the quality and keep content up to date
One duty of a Reponsible of a Fact Sheet could be to keep data quality high. To approve quality you need to be a workspace member with editing rights.
So at least one Responsible has to track changes made by a Non-Responsible user and approve the changes made. To make yourself responsible for a Fact Sheet, accept changes and then unsubscribe yourself invalidates the Quality check. This is because to unsubscribe a Fact Sheet change made by a Non-Responsible person. So you better avoid this.
You will see the following small window that explains why you cannot approve the Quality of this Fact Sheet. Please read the possible Actions you can perform.