This issue tracks the release note for the following Fedora Change:

https://fedoraproject.org/wiki/Changes/mpfr-4.0.2

If you own this change, please add additional information here that we should communicate to Fedora users.

Upstream release notes applicable to this change:
https://www.mpfr.org/mpfr-4.0.0/#changes
http://www.mpfr.org/mpfr-4.0.1/#changes
http://www.mpfr.org/mpfr-4.0.2/#changes

In my opinion, these are the ones our users are most likely to care about:

• mpfr now supports shared caches for multithreaded applications, thereby reducing memory usage
• improved caching: a minimum of 10% increase of the precision is guaranteed to avoid too many recomputations, thereby reducing CPU usage
• a small-precision mpz_t pool is used to reduce the number of memory allocations, thereby reducing CPU usage
• several functions are now faster; e.g., mpfr_add, mpfr_sub, mpfr_mul, mpfr_div, mpfr_sqrt, mpfr_set_d, and mpfr_get_d
• the mpfr_div_ui function could produce incorrectly rounded results in mpfr 3; the bug has been fixed in mpfr 4

This is a Fedora Change since gcc uses mpfr, but most users will not notice the change. I expect that most Fedora users don't even know that mpfr exists.