iCloud Find vs Find App, which is more accurate?

I've noticed some odd behavior between iCloud Find and the Find App. It seems icloud.com/find is somehow "slower" and "less accurate" than the Find App. Sometimes, icloud.com/find shows my device as offline with no location reported, while the Find App continues to update its location and status. I called Apple Support, but they couldn't explain it either.

Here's a specific case: I lost my phone yesterday after getting drunk at a bar. My friend took me home in a taxi from point A around 6 am. By 7 am, I was home and went straight to bed without realizing I'd left my phone in the taxi.

Around 10 am, the taxi driver dropped off another client near point C (I contacted him for details). He mentioned that one client passed by point C, so I suspect that's who took it.

When I woke up and couldn't find my iPhone, I checked both the Find app and icloud.com/find. The website showed my device last online at about 6 am at point A. Meanwhile, the app showed it last seen around 10 am at point C.

Strangely enough, when trying to enable Lost Mode—even though the device's location kept updating—it still said "Lost Mode will be enabled when your device is online." If it's updating its status doesn't that mean it's online? Why can't Lost Mode be updated on an apparently online device?