I am using Defender relay to carry out a deployment.
The deployment comprises of a number of contract deployments and then a number of different operations to be carried out on the contracts.
One of the operations to be carried is an airdrop of the token. This is batched in to 12 different transactions of 250 individual transfers.
Usually, it takes a little bit of time (~1 min) for these airdrop transaction to land on chain. They are big transactions that use ~ 5,515,222 gas units.
Usually the 12 airdrop Tx's eventually all land on chain and everything is ok.
What I noticed last week though was that some of the airdrop transactions seemed to be cancelled with NOOP transactions with 21,000 gas units (see attached screen shot).
I have the Defender Relay configured to a use a fast speed. Do people know any potential reasons why the airdrop transactions are (only sometimes) being replaced by NOOP tx's?