Very high background mobile data usage a few days a month

Reviewing my mobile data usage log, I see an odd pattern. I am using an iPhone 14 Pro fully updated iOS.

Every so often, like 2-3 times per month, my mobile data usage will be extremely high (1.5-2GB). Verizon lets you see data usage by day and by time. What is weird is that the huge spikes of data usage—around 1GB in a span of a half hour—occur at times when I was otherwise busy, not using my iPhone at all.

Does anyone know of any app that would auto update using mobile data with this pattern? In August it happened on the 2nd, 14th, and 17th. It was always in the late morning around 10-11am local time. I turned off cellular data updates for Photos. Any other suggestions?