looks like they just resell everything they can get their hands on at extremely exaggerated prices... I highly doubt they have any proper technical support let alone repair services.
Just stick to known brands where you can get a 3KVA online UPS for (much) less... That being said, that V7 UPS seems to be a rebranded Powerwalker/Bluewalker VFI RMG series:

Even the software is the same (viewpower). That UPS is available for over 300EUR less from powerwalker...
That is, if you *really* need such an UPS for a homelab... hint: you don't. As long as you don't live in a country/region with an exceptionally bad power grid, a plain standard line-interactive UPS is all you ever need for a homelab.
I'd rather have a look at the VI RT HID series - I run the 2kVA variant + battery pack at home and we also have 2 of them at work in places where the price difference for a cyberpower UPS was not justified.
The batteries easily last 5+ years in these UPS. I recently replaced those in my own UPS + BP after almost 7 years and they all tested 70-80% of the rated capacity. The ones @work we replace after 5 years usually still have >80% capacity compared to new ones.