A search for "wagering requirements example" usually comes after a bonus has vanished, taking its winnings with it. The cause is almost always a condition in the terms: a deadline that passed, a withdrawal made too early, a cap on winnings or a clause about irregular play. Each of these can be seen in advance, and a short read of the terms shows which of them apply to a given offer.
Casinos can change their bonus terms, and most promise that a bonus already claimed stays under the version accepted at the time. The promise matters only if the version can be shown, so saving the terms on the day an offer is taken is worth the minute it costs. The same goes for anything support agrees in chat: a saved copy of the conversation settles more disputes than anyone's memory of it.
Many bonuses limit how much can be withdrawn from winnings made with them, often as a multiple of the bonus or a fixed amount. Winnings over that limit are taken back at conversion, even after the full requirement has been met. The cap is easy to miss because it appears in the general terms instead of the offer page. On a small bonus it can make a large win on a volatile game worth only a fraction of its size.
Bonus terms include clauses on irregular play, and they are written broadly. Typical examples are betting on both sides of an even money bet, switching to low risk play to clear wagering, raising stakes sharply after a bonus is converted, or opening more than one account per person or household. A casino that finds such a pattern can void the bonus and its winnings. Reading the clause shows which patterns a casino names, and which ones it leaves to its own judgement.
A limit on how much can be withdrawn from bonus winnings, often a multiple of the bonus or a fixed amount; anything above it is taken back at conversion.
The bonus and any winnings still tied to it are removed, however close the requirement was to completion, and the clock often starts at the deposit.
A saved copy proves which version of the terms applied on the day the offer was taken, which matters if the casino later changes them.
Casinos can revise their terms, though most promise that a bonus already claimed stays under the version the player accepted at that time.