BlockExplorer - https://explorer.mainnet.near.org/blocks/2RPJGA17MQ9GAtwSVuVbasuosgkWqDgXHKWLuX4VyYv4
i am able to query starting from block - 9820221.
Can any one help me understand why this is the case and if there are other explorers where i can query the blockDetails
mainnet started from block height 9820210 (see mainnet genesis config), so there are no blocks before that one. The first 3 blocks are missing due to validators being offline or something like that, so the first produced block is 9820214, and you can query it: https://explorer.mainnet.near.org/blocks/CFAAJTVsw5y4GmMKNmuTNybxFJtapKcrarsTh5TPUyQf
Blocks before 9820210 were produced in mainnet running before July 22nd, 2020, but for some reason NEAR needed to restart the network from genesis, and thus we dumped the state as of block 9820210 and called it a new genesis, and that was the start. You have no access to the history before that moment, you can only inspect the state as of genesis, where certain accounts exist with certain balances, contract code, and states.