Ozempic pills for weight loss - will taking them affect how long my fillers last?

First of all, best of luck on your upcoming weight loss journey!
I wouldn't worry too much about this having a significant effect on your filler's longevity. While some people's metabolism may cause filler to break down faster, I wouldn't think the effect of adding in a GLP1 would make a drastic / noticeable change on this.
The combination of weight loss, medication, potentially adding in more exercise can all increase metabolism which may have an effect on your filler - but the benefits of all these things definitely outweigh the potential downside.