In Belgium since 2002, you can perform euthanasia on someone else. [E]uthanasia is defined as intentionally terminating life by someone other than the person concerned, at the latter’s request.

Other reporting seems to be that this wasn't a case of botched euthanasia though. It was when sedatives failed that the nurses tried to put her out of her misery: https://www.newsweek.com/nurses-allegedly-killed-cancer-patient-pillow-sedation-1825599