Thanks for reaching out!
After reviewing your screenshot I agree with your analysis that this does not appear to be a local network issue as the first hop (your router) shows no signs of an issue. Considering this, it appears that the problem starts at the second hop (10.135.128.1) in the route as you can clearly observe patterns of latency/packet loss that align with that shown at the destination (final hop).
In communicating the data you have collected with your ISP I suggest checking out the following article which is focused on building a case with your ISP: Build a Case
If this leaves you with any other questions please let me know!
Best of luck,