The web description for a power inserter is to send power back up the cable so that it can power kit. That doesn't match what a powered splitter does - which is to amplify the incoming signal, but not power anything.
So I'd agree with what @JOE-C said, and that it's an FTTP install
When checking last night I also came across this page which describes a FTTP install from a customer perspective
https://richardglover.co.uk/2017/07/virgin-media-fttp-install/
It includes a picture of a Vector optical node which is taking power from the single coax that's also supplying the Hub and / or TV for services, rather than using the separate power in.
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I work for Virgin Media - but all opinions posted here are my own