Is taproot considered nonstandard to older clients?

[Bitcoin]

Is taproot considered nonstandard to older clients?

When asking an older bitcoind node to broadcast a transaction which includes or spends a p2tr output, how will they respond? Will they broadcast the transaction? Will only certain bitcoind versions broadcast them? Which ones if that's the case?

I'm not asking if it's possible to detect if a user's bitcoind node will broadcast the p2tr transaction, which can be accomplished with getblockchaininfo checking the bip9 version bits supported.

Source: Is taproot considered nonstandard to older clients?