The Great Mouse Detective (1986) was earlier and the ending sequence is CG (printed out and traced onto cels so traditional 2D characters could be drawn on top).
That's a good point. What's funny is that "The Great Mouse Detective" was actually the film I was thinking of this whole time - I believe the ending sequence took place in Big Ben, and it looks quite good by 2024 standards. But I forgot the name of the movie and assumed it was "Oliver & Company" because Oliver is a plausible name for an English mouse :)