I believe one of the possible reasons for the spatial defects, like cosmic strings, not being found could be that they've essentially stabilized over time which

I believe one of the possible reasons for the spatial defects, like cosmic strings, not being found could be that they've essentially stabilized over time which means the slight differences between patches of spacetime effectively mended and thus wouldn't leave anything detectible. But I do believe there's still some consensus that we should see some of these defects in deep sky observations despite this possbility.