Bonuses is pretty common on crypto casino. Crypto casino like Metawin which you can find on my signature space always have different bonuses every day that you can take advantage.
though it is not a bonus or freespins I just want to add that they often have giveaways on their X account(formerly known as Twitter), so @OP if you are curious about it you can visit their X account and join their giveaway.
If I had my own sportsbook/casino I would be giving the maximum amount of bonuses to reward customers but the majority do not do this.
that's because casinos/sportsbooks are businesses while some can be generous with the free spins or bonuses they would not give too much since it could affect their profits which is what they are always after.