I'm on "Pop!_OS 20.10".  Current versions:

* Linux kernel 5.11.0-7612
* gcc version 10.2.0 (Ubuntu 10.2.0-13ubuntu1)
* GNU gdb (Ubuntu 9.2-0ubuntu2) 9.2


% ./python -m sysconfig | grep CFLAGS
        BASECFLAGS = "-Wno-unused-result -Wsign-compare"
        CFLAGS = "-Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O0 -Wall"
        CFLAGSFORSHARED = ""
        CFLAGS_ALIASING = ""
        CFLAGS_NODIST = ""
        CONFIGURE_CFLAGS = ""
        CONFIGURE_CFLAGS_NODIST = "-std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -Werror=implicit-function-declaration -fvisibility=hidden"
        EXTRA_CFLAGS = ""
        PY_BUILTIN_MODULE_CFLAGS = "-Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O0 -Wall -std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -Werror=implicit-function-declaration -fvisibility=hidden  -I./Include/internal -I. -I./Include -DPy_BUILD_CORE_BUILTIN"
        PY_CFLAGS = "-Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O0 -Wall"
        PY_CFLAGS_NODIST = "-std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -Werror=implicit-function-declaration -fvisibility=hidden  -I./Include/internal"
        PY_CORE_CFLAGS = "-Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O0 -Wall -std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -Werror=implicit-function-declaration -fvisibility=hidden  -I./Include/internal -I. -I./Include -DPy_BUILD_CORE"
        PY_STDMODULE_CFLAGS = "-Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O0 -Wall -std=c99 -Wextra -Wno-unused-result -Wno-unused-parameter -Wno-missing-field-initializers -Werror=implicit-function-declaration -fvisibility=hidden  -I./Include/internal -I. -I./Include"