Constant intermittent latency at all hours of the day, effects all web-enabled apps

For the last month and a half, my home network has been experiencing brief bouts of severe latency (e.g. when a Discord call gets tinny, the ping exceeds 5000ms). This happens throughout the day and effects any application that interacts with the network. An Xfinity technician has already been out to our residence to check and shore up the cabling (some fittings got replaced, the cable routing to our discrete modem was replaced) and the issue continues to happen.

 I am using an SB8200 modem and a LinkSys MR20EC router; I have set the router to use the Cloudflare DNS for IPv4 devices (doesn't have controls for IPv6, doesn't seem?). These devices are less than a year old and were purchased together, and these symptoms did not occur for the first 5 or so months of service at this residence.

 I ran some traceroute commands during tonight's constant barrage of latency spikes (seven in the last hour alone), pinging Google and Discord and getting the following results.

Can anyone assist me in figuring out of this is some sort of routing issue with local infrastructure? Or any other suggestions with regard to home network settings? Maybe divine out some information that I can bring to Xfinity and go 'fix your local [Edited: Language]'?