From https://bitcointalk.org/index.php?topic=1786.msg22119#msg22119:

We can't safely do OP_BLOCKNUMBER.  In the event of a block chain reorg
> after a segmentation, transactions need to be able to get into the chain in
> a later block.  The OP_BLOCKNUMBER transaction and all its dependants would
> become invalid.  This wouldn't be fair to later owners of the coins who
> weren't involved in the time limited transaction.
>
> nTimeLock does the reverse.  It's an open transaction that can be replaced
> with new versions until the deadline.  It can't be recorded until it
> locks.  The highest version when the deadline hits gets recorded.  It could
> be used, for example, to write an escrow transaction that will
> automatically permanently lock and go through unless it is revoked before
> the deadline.  The feature isn't enabled or used yet, but the support is
> there so it could be implemented later.
>

Unfortunately, limiting the maximum block height for a specific transaction
would have exactly the same problem as cited above for OP_BLOCKNUMBER.

On Fri, Apr 9, 2021 at 7:21 AM Erik Aronesty via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> is there any way to specify a maximum block height on a transaction?
>
> ie: this tx is only valid if included in a block with a certain height or
> less
>
> i feel like this would be useful
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>