There is a flaw in Oneui7, if you hide an app , you can't find it via the Oneui7 search for sure but if you have google assistant search bar , and if you type the hidden app there, it shows it right then and there.
"Hiding" apps isn't really for security—as you can go to home screen settings and view all the hidden apps and put them back with zero passcode needed. If you want an app secure, secure folder is needed.
It's really a feature to organise your home and apps screen more than as a security feature as others have already mentioned. Actually hiding apps from Google's own search would more than likely require root access and therefore is unlikely to be implemented in any official capacity.