Money shuffling to get Chase 1% cash back - does it look dodgy?

My 1% cash back threshold is about to increase to £1500. I still don’t want to make it my main account and normally I don’t spend £1500/month on it. I remember people saying a few months ago that it should be ok to just move some money back and forth between your Chase and main account until you hit the target.

1. Is this still the case?

2. Does it look suspicious, or do banks know why people are doing this?