Imagine there are a series of reorgs happening because of maybe some fee sniping event or something else, doesn’t matter.
If that happens for over than 2 hours, then new blocks will not be able to mined with their current timestamp anymore, otherwise they wouldn’t be accepted? In such a case will the chain have to proceed with invalid block times forever after the reorgs end?
No. The 2-hours rule is checking if the timestamp of a block is not more than 2 hours in the future. A valid timestamp for a given tip cannot become invalid as time passes.
There are two restrictions on the timestamp of blocks:
- A consensus rule that the timestamp of a block must be strictly larger than the median timestamp of its 11 predecessors (parent, grandparent, great-grandparent, …).
- An acceptance rule that the timestamp cannot be more than 2 hours in future (compared to the verifier’s local clock).
Neither of these rules tightens when a reorg happens. The first rule widens (as the reorged out blocks disappear from the median timestamp calculation), and the second rule is unaffected (it continues to allow more and more as time passes).