Just switched, strange smart meter behaviour

I’ve just completed a switch to bulb and I’m now seeing a bit of strange behaviour from my smart meter.
I believe it’s a gen1 meter so I was expecting it to just stop working. However, I’m still seeing usage on the display in my home, but only for electricity.
I’ve checked through it and the gas tariff is displaying the cost as £0. The electricity tariff, appears to be displaying a cost but I think it’s from my previous supplier (British Gas - 16p…ish) as I think bulb is a little cheaper than 16p??
I just wondered what’s going on here? Has anybody experienced this before after a switchover with a smart meter?