Nobody said it's "true", whatever that even means for a model. The claim is that it's the best anyone has been able to come up with. And not for a lack of trying.

Everybody also acknowledges that there are issue with DM, it's just that every other known model has bigger issues.

Ha, my bad

When you write "this is the [..] most common objection laypeople have", I understood "In contrast with the experts who know better"

Of course, if as you say, everybody knows that this is a wrong, specifying "laypeople" seems unnecessary

You seem to have a concept that a scientific model is either "true" or "wrong", but that's not case. All models are wrong, but some are more useful than others. It's better to judge models by their ability to describe reality, and that is not a binary property, but a continuous one.

What if we one day come up with a Theory of Everything that mathematically explains it all?

That model would be “true” no? Assuming of course that it’s possible to come up with a list of observations that covers “it all” and we won’t one day see something weird and new that contradicts our theory.

It’s not a good objection. It conveniently ignores the actual data.