Yea that makes sense that the USD deposits are FDIC insured but not the crypto deposits. There's no way in hell the govt. would ever insure crypto deposits lol. Some exchanges do have private insurance, which is exactly how USD bank deposits should be insured.
Despite the name, the FDIC is NOT insurance because they don't price based on risk. It's one of the many ways that banks are encouraged to take ridiculous risks with people's money. If it was real insurance, then the banks could never afford it with how they are currently run, and then people wouldn't deposit their money with them (presumably).