> I know one C++ library that caches data but never evicts. Instead, the library author expects you to restart your app every 24 hours.

It may not be as simple as "that's our policy". I worked at one place (embedded C++ code, 2018) that simply reset the device every 24h because they never managed to track down all the leaks.

Finding memory leaks in C++ is a non-trivial and time-consuming task. It gets easier if your project doesn't use exceptions, but it's still very difficult.