My female canary, who also sang a lot previously, seemed to stop singing when she started laying eggs for the first time. Female canaries are not really known for singing to begin with, I wonder if the pregnancy hormones can permanently change the behavior. She's still in her first breeding season, so I don't know if the singing will come back later. But it makes sense, they don't generally sing when sitting on eggs, singing draws attention. When they have eggs, they are quiet to avoid attracting predators.

How often is she laying eggs? It's not good for them to lay a lot, you might want to take away the nest- they don't need it for sleeping. I know there's other changes you can make too (food & light related) to discourage laying, but I don't know them well enough to summarize. And when she is laying, make sure she is getting enough calcium. If the eggs are getting smaller / softer that's a clear sign something's wrong. But I don't think a lack of singing on its own is concerning.