This is a Tesco and their card acquirer sadly as @Ordog has said. We have tried resolving these issues but their acquirer doesn’t seem to fix the issues no matter how often we request this through Mastercard or directly to Tesco themselves.
Some Tesco stores are aware of the fact that they present for the payment under a new authorisation code (causing a double payment) and will try and help you and refund it quicker. Others will just blame us and we need to collect enough evidence to raise a dispute. I’d always recommend getting a receipt from Tesco if this happens so we can refund you as quickly as possible if this error does occur.
As for why you see this more with Monzo instead of other banks is down to us showing authorisations instantly in your account, this means that while the payment is still pending you’ll see 2 payments. This should reverse in 8 days.
Hope this helps 