DECISION MADE means just what it says. IRCC, or rather the citizenship officer in charge of your case, has made a decision on your application.
Whether that decision is an approval or refusal, my understanding is that depends on what issues they had with your case at the test/interview. If the only issue was the residence requirement, then DECISION MADE means an approval, as citizenship officers can't refuse an application just for not meeting the residence requirement. If they're not satisfied that you meet the residence requirement, no decision is made and your case is referred to a citizenship judge.
Before the new law, officers had to refer cases to citizenship judges for every issue, not just residency (i.e. language proficiency, knowledge of Canada, criminal prohibitions). Now they don't. Officers decide one way or the other on all these issues, except residency.
So if they had concerns on your case other than residence, a DECISION MADE could be a formal refusal. Otherwise, it's an approval.