No, it depends very much on whether she burst into song an insufferable amount and whether she is as flat as a pancake.
If she is a terrible singer or very intrusive with it and always bothering and attention seeking, they may have a point. It would be discourteous and intolerant of the OP to continue if this is the case.
She needs an independent assessment of her voice, not a long ago choir, and to be realistic with herself about how much she is doing this.
It is possible they are just being horrible to her - if so, that needs further investigation.
I know two young women who are thoroughly embarrassed by their mother who will burst into song at the drop of a hat. She bought a gold suit from a second hand shop, a shiny stage type suit, and wears it on evenings out (it belongs in a musical number on a stage, but it gets attention). The other day she was walking through the mall with deely boppers on, a 61 year old woman hoping to be looked at (yes of course age is relevant, we expect everyone to learn more self awareness as they age). There is recent video footage of her cavorting, attempting to moondance etc on a night out with her daughters, putting herself in the middle of a group and basically demanding attention. When Singstar was popular she bought it and would force the family to join on karaoke competitions.
She is talentless, at both singing and dancing and they find it utterly cringeworthy and embarrassing. She seeks attention and lives in a bubble where she's actually quite good.
I will confess this is the sort of person I thought of when I read the OPs post. I could be wrong.
On the other hand, the woman I mentioned is quite entitled to behave like this, it's harmless and it brings her pleasure. But others are entitled to hate it too, and if they live with you it can be problematic.
It is absolutely impossible to know the reality of this situation, as the OP must be treated as an unreliable narrator. We all think we're far better than we are at certain things, this might be one of those things.