[  168s] ../../grub-core/net/http.c: In function 'http_establish':
[  168s] ../../grub-core/net/http.c:414:48: error: operand of '?:' changes signedness from 'int' to 'enum <anonymous>' due to unsignedness of other operand [-Werror=sign-compare]
[  168s]   414 |                 data->filename, server, port ? port : HTTP_PORT);
[  168s]       |                                                ^~~~
[  168s] ../../include/grub/misc.h:38:88: note: in definition of macro 'grub_dprintf'
[  168s]    38 | #define grub_dprintf(condition, ...) grub_real_dprintf(GRUB_FILE, _LINE_, condition, _VA_ARGS_)
[  168s]       |                                                                                        ^~~~~~~~~~~
[  168s] ../../grub-core/net/http.c:416:42: error: operand of '?:' changes signedness from 'int' to 'enum <anonymous>' due to unsignedness of other operand [-Werror=sign-compare]
[  168s]   416 |                                   port ? port : HTTP_PORT, http_receive,
[  168s]       |                                          ^~~~

and it's reported as GCC issue here: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107314