This past week there was a consensus failure due to a non-deterministic bug with durable nonce transactions. You can read the full post-mortem here. Durable nonce transactions were temporarily disabled until the bug has been patched. The clock drift issue from the past week was patched with a feature activation this past Friday. Currently the on-chain time and UTC time are close to matching. If you're ever interested in new features being created, be sure to check out the feature-gate issues.
What are Durable Nonce transactions?
Every transaction on Solana requires a recent blockhash in order to be processed. Blockhashes expire after 151 blocks at the time of writing. Some signers, such as offline or custodial wallets, will not be able to sign transactions fast enough to produce a transaction with a valid recent blockhash. To solve this problem, you can use durable nonces.
Durable nonces enable transactions that do not expire. A wallet can create a nonce account which stores a recent blockhash to be used with transactions. When creating your transaction, you specify your nonce account to be used instead of a state recent blockhash. The transaction will then advance the nonce to a valid recent blockhash to use in the transaction.
A full example usage of durable nonce transactions can be found on the Solana Cookbook.