To claim a bonus, you must meet the turnover requirement first . This is why withdrawal requirements change. If you claim $10 bonuses and after deposit $10, if the bonus has a minimum turnover requirement of 10x, you must meet this requirement. If you don't meet this requirement, you may not be able to withdraw. Deposits generally require 1x turnover requirement, while bonuses generally require 5-10x turnover requirement. Each casino has its own rules regarding this. However, this is based on the casinos I frequently use, other casinos will likely have different rules.
The TO requirements are more difficult than the bonus, so I never chase it because it will be higher than the TO with a deposit, which generally only requires 1x --- but it is reasonable for casinos to enforce rules with their bonuses so that not everyone can claim bonuses easily.
Even new casinos offer tempting initial deposit bonuses, but I'm still not interested, especially since chasing these bonuses will be difficult to meet the wagering requirements.
Some bonuses even require wagering requirements exceeding 10x.