Do you have any knowledge of in what situations sportsbet ask for KYC. Is there purely a withdrawal threshold where they ask for KYC, and if so, what is that?
Yes, there is a withdrawal threshold for KYC here's the part that was mentioned in their terms and condition.
Also don't use RBF(replace by fee) on your deposits as it will trigger a "freeze" on your account, you'll be forced to contact the support and the security team to fix this issue.
9.2. Sportsbet.io reserve the right to carry out additional KYC verification procedures for any withdrawals exceeding the equivalent of 1 Bitcoin or €2000 as regulated by our gaming license. Account Holders who wish to recover funds held in a closed, locked or excluded account are advised to contact our Customer Support.