That’s not good!
Since your Monzo account’s held in the UK, then assuming that you’re funding it from a UK account, you can top up a lot more.
Monzo’s limits are listed here -
I haven’t heard about any issues relating to topping up from debit cards though so I’d recommend asking customer support about that. If you’re using Monzo.me to top up, there are additional limits but that one’s not listed. Topping up from the card(s) you’ve got set up in the app / Apple Pay is probably your best bet or by bank transfer.
5 per day seems like a lot though…why not top up more? You can always freeze your card from the app if you lose it…