Addiction problems never stop at home. Everyone suspects it, some know it, nobody talks to co-worker C. about it. Addiction is a problem that many supervisors avoid by looking away: for fear of worsening the addiction by confronting it. - But the permanent short absences continue...
If you wait carefully for the right time, you may be waiting too long. Waiting can be dangerous for those affected. The duty of care is a legally enshrined protection that must be taken seriously: as protection for those directly affected and also for people around them.
In such situations, it requires a lot of experience in conflict talks and sustainable counselling strategies.