[BUG] Error "Send Failed : mandatory-script-verify-flag-failed (Signature is found in scriptCode) (code 16)" on webwallet testnet

[nenantonov]

Description:
In some cases webwallet.hydrachan.org will not send and error Send Failed : mandatory-script-verify-flag-failed (Signature is found in scriptCode) (code 16) will be displayed.

Wallet to replicate the error on testnet:
Address: TuPAcZZVBKuuuFR3WVSwyKms5F42Qnj4xM
Pr. key: cNafonMGsnSUCvcthdWGCujTFR1qiKUdq9iFHGjAEv3Wf29MebRn

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Additional context:
The error seems to be related with a certain set or a high amount of UTXOs. Rearranging or consolidating the UTXO set is reported to solve the error.

[nenantonov]

This error happens when the address contains coinbase UTXOs (the address is staking or was used for staking).