iterator_concept in C++20

Some C++20 library may already set iterator_concept to std::contiguous_iterator_tag, then ranges::contiguous_iterator will be false.

Or if I set iterator_concept to ranges::contiguous_iterator_tag, std::ranges::contiguous_iterator will be false.

So is there any reason not to make ranges::contiguous_iterator_tag a typedef of std::contiguous_iterator_tag when using C++20? If so, how to make my contiguous iterator fit C++20 and range-v3 together