See PHI1616, which requests adjustments to the strikethru style for checked-off items like this:
Although that issue has larger scope, I think the strikethru is generally unnecessary and undesirable. It makes the items harder to read, there's at least one tricky bug with it interacting with icons in T12865, and I don't think it makes things significantly more clear. There's a mild "only communicating information through the use of color" accessibility issue, but the checkmark itself is still checked and that's pretty high-visibility.
I'm just going to get rid of it and see how far we get with that.