The difference in used toolchain could make the difference, but I don’t know whether that config is user-controllable.
Thought differently: There is a Zephyr example which uses the TCP stack at platform-ststm32/examples/zephyr-net-https-client at develop · platformio/platform-ststm32 · GitHub. And there are also lots of calls into exit() in there. However, the example builds perfectly fine for me in the given configuration (F7 Discovery board) – so maybe we missed something in the config after all? platform-ststm32/examples/zephyr-net-https-client/zephyr/prj.conf at develop · platformio/platform-ststm32 · GitHub