Loading tips do two things at once: a progress bar (or spinner) tracking actual load progress, and rotating text giving the wait something to read. Tips crossfading every few seconds is a classic perceived-performance trick — the actual load time doesn't change, but the sense of "I was doing something while waiting" offsets the boredom.
The bar doesn't have to track real progress precisely (asset loading is hard to predict) — but it shouldn't look frozen either, so a low-effort continuous motion (a striped animation, for instance) is common even when true progress is unknown.
Tip content should actually be useful or interesting — controls, strategy, a sliver of lore. Generic or repeated tips just reinforce the feeling that the load is taking too long.
When to use
Loading or transition screens that take more than a few seconds. Unnecessary for instant transitions.