Enable concepts support under normal -std=c++2a and not under -fconcepts-ts, which is now deprecated.
Looks like you picked up an unrelated change here; please revert this.
I think everything is done other than P0848, so according to https://isocpp.org/std/standing-documents/sd-6-sg10-feature-test-recommendations#__cpp_concepts the appropriate value to use here is 201907L.
As discussed off-line: I think P0848R3 is not yet done, so that row should be left as "No" instead of being marked as "Clang 10". (I'm assuming you'll land https://reviews.llvm.org/D73155 first, so P1616R1 will be done before this goes in.)