We are missing a bit of context for the data represented in the picture, but this could be an issue on the ISP equipment upstream of you (perhaps the devices are being overloaded by processes around these times) or it could be an issue on the line itself. A while back there was a post where someone suspected their cable internet was being used by a neighbor (if you live in an apartment building, this can be a concern). I believe the issue was tracked down to no MoCA filter being used in line. Alternatively, and this is probably more likely, it could just be a computer issue. You may have a lot of automatic computer processes running around that time, which may put strain on your allotted bandwidth.

On prosumer side, it allows for higher LAN transfer speeds and also allow for higher WAN speeds (such as 2.5Gb) and future proofing. They are common in the enterprise environment when one device aggregates the data from many other devices.