One of the limitations of Hive is that an account can only deliver a certain upvote value (based on its total HP and VP%). You are getting the maximum vote that Hive SBI is capable of delivering right now (if you look at each of those individual votes, they are all 100% upvotes).

You can also see that most of the accounts have very low VP%. Hive SBI made a decision in 2020 to let most of their leased HP expire without renewal, in order to see what VP levels would actually look like without paying for leases. That caused the VP% levels to fall a lot. With a more accurate baseline in mind, regular lease orders are being made on dlease to bring HP up (which will allow VP% to climb back up). As HP and VP% climb back up, the maximum deliverable upvote will rise and this problem will eventually resolve.