Smart Meter jumping up in price in very odd way. Help?

I am utterly baffled. I had a smart metre installed by Octopus about a month ago. It’s been great so far, and it’s very helpful at keeping our usage down and we are on track to spend around £90 this month on Gas and Electric which we are very much okay with. However the past couple nights we’ve noticed some strange jumps in price. So I was getting ready for bed, and my partner was already in bed. I had already turned off everything in the Living room so nothing was on standby. Everything was off in the kitchen as well. All that was using power was the fridge, a bedside lamp, a set of fairy lights in the hallway and both of our phones on charge. So I looked at the smart metre on the way to the bathroom and it read £0.06 spent on Electric and £0.00 on Gas. These seemed very accurate and they added up very nicely with the Smart Metre saying we were using £0.06 per hour and the time was 0:56. I was very relieved to see this after the trouble we’d been having with prices jumping up, so went and did my nightly routine: the usual teeth brushing, face washing, toilet flushing combo. This all took me about 20 minutes in total. On the way back from the loo, after checking the doors were locked and plugs were off, I checked the smart metre again. Imagine my complete and utter befuddlement when I come back to see that in the span of around 20 minutes the Smart Metre had jumped up to £0.57 from £0.06. Nothing had changed, no more plugs had been switched on, but suddenly we’d spent almost the price of a Wispa Gold in Electricity. Surely somethings going wrong? Does anyone have any help?

And yes, before you ask, I have turned it on and off again, thank you Roy.

I have photographic proof as well.