Operators frequently cap the maximum stake for purchased features at a lower level than for regular spins, so the 100 dollar bet you can place normally might drop to 20 when buying. This matters for anyone trying to clear wagering quickly or just preferring bigger purchases. A quick look at
https://thebonusbuyslots.com will show the buy specific bet ceilings for the major providers alongside the regular limits, which vary more than you would think. Crypto sites tend to allow larger buys, though that is not always a good thing.