We just boarded the Rotterdam today in Amsterdam. On embarkation, we were given a note saying indoor masks are mandatory except when eating or drinking, due to a few crew members and guests testing positive on the last cruise.
Our stateroom had four N95 masks in it (for the two of us) and our cabin steward said he would give us new ones every third day, or sooner upon request.
The Chief Health Officer was in the embarkation area to answer questions, as this mask policy is different than the official posted policy - and different than when we sailed on the Rotterdam just last month in the Caribbean, when masks were optional.