Why is a suspicious program draining my battery with GPS usage?
It's the UID of a removed app.

For such a number like 10118, it is the Unix UID for a user app (u0_a118).

There must have been a power-intensive app like a big game and you uninstalled it. Then there's nothing but its UID left, which is used in system logging.

Android does not log by app (for user apps), but its UID instead. So when you view battery usage, Android tells you the list by process UIDs, which contains one that has no app associated to it. Android cannot determine what app that UID is for, so it chooses to give you the UID directly, and that's the number you see.