Does Playwright wait for "load" event to be fired by all firames?

I have very interesting but also frustrating problem in our tests. Our tests are failing quite frequently with following error (screenshot). I suspect that Playwright starts listening for "load" event too late, after event was actually dispatched.

So I prepared a workaround which dispatches "load" event manually when app initialized. This reduced number of failures significantly but they still happen. I have 100% confidence that I am dispatching this "load" event.

So I started thinking if Playwright is also waiting for load events from iframes that are in the page. I think I recall some code in PW repo that tracks iframe states in the page but I don't remember where it was and what actually it was doing. Hence my question. I would really like to understand how waiting for "load" event works in order to solve this problem in our tests.