Xbox Game Bar just sounds like bloatware to me, but to each their own I guess. I will say though that the features you mention does sound like Riva Tuner, and why that conflicts with this game is because you can set it up to be more or less aggressive with feature implementations which is what causes the problems. So if you can, set it up to be less aggressive or just disable it completely in task manager and see if that works.
Also, try disabling anti-virus software before running the game to see if that has any effect (If it's just Windows anti-virus, then it's fine as that does nothing anyway). For some reason, anti-viruses can occasionally get in the way of games. Same thing with VPN if she has one.
The thing about brand new computers is that they should always be stress tested as hard as possible to see if there's any faults in the hardware because warranty's aren't forever and the sooner you prove it's broken or stable, the better in the long run. By stress tests, I mean CPU Burn-in test, GPU simulated tests as well as a demanding game test for PSU (or run all 3 at the same time and bring the PC to it's knees in fps). That 650watts PSU you mentioned is within the bare minimum for that hardware, but if it's an average or poor quality PSU, then it's possible it's not enough. If you have a spare PSU laying around, you could try connecting the GPU directly the spare PSU and turn that on and then the PC and see if the game will load up. (spare PSU will need the green wire connected to any black wire on the 24 pin connector, unless all wires are black in which case use an adapter to be safe)
No tuning tells me the ram is running at 2100MTs with DOCP off, which hinders some performance. Go in BIOS and enable DOCP and set the ram to the recommended settings. Having 4 sticks of ram could get a little finicky with stability but it should be fine given the generation of CPU being used.
Right now, in my opinion, all fingers are pointing at that Xbox Game Bar as the culprit. It's definitely either a hardware issue or software conflict. It's just a matter of ruling things out and narrowing it down to the right thing.