We disabled the apple and google pay integrations on monzo.me last month. This is because we had to upgrade the version of the Stripe integration that powers it, in order to be compliant with the new Strong Customer Authentication regulations. The Stripe update requires more work on our side to make Apple and Google pay compatible with it again.
The team that owns monzo.me (the one I work on 
) is currently laser-focused on shipping our in-house Faster Payments gateway - to replace an unreliable third party. The only slot Faster Payments themselves have available in their release schedule is in early November. It was a tough prioritisation call to make, but we can’t afford to distract ourselves with other work until it is complete.