I have the exact same problem on rocket league. Sometimes it is harder to notice than other times ... Its even worse on CSGO. That is the worst game for it IMO. Yesterday I used USB tethering with my phone (you can do it too if you have a phone which can hotspot, mine is a samsung S8) to connect my PC to the internet, and boom.. no ping spikes, zero packet loss, completely normal again.
After months of trying to fix my connection with resetting routers and changing my software it turns out it is Virgin media who has the problem.
Think about that for a second, my phone which is completely wireless and connects to a 4G tower, provides a completely stable connection compared to a WIRED connection which virgin media uses in their underground fibre network. Insane! It is supposed to be the opposite where Wireless is jittery and unstable, not wired... shows you how badly set up the VM network is in oversubscribed areas.
I recommend you switch. Or if you can't do that, you can at least connect your phone to your PC and enable 'Hotspot via USB tethering' to use your phone for internet. I have read the other post on this forum which has nearly 60 pages, and they haven't fixed anyones internet for months. Everyone has the same problem, rubber banding, high ping and packet loss. They have been giving empty promises since March to people saying they will 'repair' soon. They are just waiting for the lockdown to end, when less people will be using the internet and their network will be able to cope again.
I have the exact same problem! Rocket League is the worst for it but this happens on COD Warzone, FIFA, literally every game I play. So frustrating to say we pay a fair amount for the HUB 3's internet etc and we're not receiving the service we're paying for. Nobody seems to be able to help in the slightest. I'd love for an engineer to come out but there's no way of being able to get one sent out to me without proving my problem, which I just can't put into words for someone on the phone to understand the issue.
If someone from Virgin could please help out here, that would be much appreciated as I'm getting incredibly stressed about this and im seriously considering a switch if nobody helps me with this!