I see a different tx with nonce 822 from that account at the same time: https://etherscan.io/tx/0x3cb8acdffebfce9fabab7891afecc0db7e5059dca72f24e7f03eacfcd7e75ac3 Is it possible you are posting multiple transactions with the same “future” nonce?
For example, if you current nonce is 100, and you post two different transactions w/ nonce 102, then “fill the gap” with nonce 101, only one of the nonce 102 transactions can ever be mined.
Meanwhile, again if your nonce is 100, and you send two different nonce 101, the 2nd transaction will be considered a “replacement” transaction and will overwrite the second transaction has a higher “gas price” than the first. However, in this case I don’t think that’s what happened since both transactions seem to have the same gas price.
In short, my suggestion is that you keep a record of the nonce of every transaction you send, and double check that each transaction has a nonce 1 higher than the previous and that you don’t introduce any duplicate nonces or nonce gaps. If the issue happens again and you have the record of all nonces used, the parameters of the transactions, and the resultant tx hash it should be easier to debug the root cause.
Hope this help!