Deferred admission but funding not guaranteed
In brief, in academic mathematics, if you are "accepted" but without promise of funding, it's a very weak offer. The fact that you got funding this time around is certainly positive, but there's so much volatility involved that I think it would be a dangerous mistake to view the situation as so much promised to you (it's not) so that you have a complete obligation to go there and nowhere else. A promise of funding should be construed as obliging you to either keep your promise or decline in advance, but mere admission, without funding, while not nothing, is barely something, either.