BQM shows a mediocre broadband connection - because cable internet has some peculiarities over a true FTTP connection, you'd expect the yellow fringing that you see between midnight and 10am all of the time. The spikes in the afternoon and evening, those are not what you want to see, and might explain why you are experiencing a poor connection. That latency is between your hub and the Thinkbroadband test systems, so there's no wifi involved, this is a showing only the broadband connection quality, and in 99% of situations, any problems occur on the local Virgin Media network from your house to the equipment that sits at the head of the local network.
Because the connection overnight is good and consistent, and problems build through the afternoon and mid evening, I suspect that the cause is low level capacity problems on VM's local network. In most situations like this VM will insist that by their data there is no problem. And for them that is true - lots of customers, all paying their bills, Spectrum is Green! For you it's not so good - VM have sold more contracts than their equipment can support, the impact is momentary queuing of data packets at the head of the local network, and that affects latency when the network is busy, giving you latency spikes that are poor for gaming (as well as affecting Teams and videos calls), yet VM will insist on their grandmother's grave that that there's no fault.
What can you do about it? Nothing, I regret to say. Complaining about capacity issues has been tried many times over the years and doesn't work. Staff who work this forum have to abide by the Three Wise Monkeys rule that VM operate as policy, so I'd be surprised if they say there's a known problem, or that your BQM shows one. And at the level observed I'll say that VM won't recognise a problem, and therefore won't do any of the often expensive and complex work to increase capacity.