Yeah I agree with Carlton here. The segwit soft fork meant that legacy blocks are still accepted after the fork but this doesn't work the other way... From what I can tell the signed part of segwit transactions just get ignored by full nodes before v13 and they just take the 150 byte transactions (as an example from the standard size) because the longest chain is running with them (and there isn't a reasonable rival).

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@op why do you not want to mine segwit txs, anyway yes they won't be segwit compliment if the coinbase pays to legacy but you're also not doing much to help the network by confirming transactions if you just pass in your own.