The biggest "risk" for my use has been that Ocado's predictive pre-filling of my weekly order is just good enough that I've gotten complacent about checking the orders, but it's not quite perfect, so if I miss the deadline, I might occasionally get stuff I didn't need (this is optional functionality - you can just place orders when you need them too and you can tweak what is included to have more control).
Ocado, the company in question is licensing various parts of their tech stack. E.g. in the US they've licensed to Kroger (which also took a 5% stake): https://www.businessinsider.com/ocado-kroger-amazon-online-g...
Between that, and the option of (more expensive) rapid deliveries from takeaway delivery companies like Deliveroo, or from the multiple different 15-minute grocery delivery companies, grocery stores just seems like a nuisance to me at this point. Of course my judgement is influenced by the fact that I don't have a car so not needing to drag shopping on foot or bus makes the leap in convenience far more significant than for a lot of people.