I've dealt with crumby, unfix-able internet for 3 years, and I've had enough. I'm trying to figure out the exact cause of my issues rather than wait for my ISP to tell me everything is fine for the literal hundredth time.
I'll try not to veer off onto angry tangents, I swear.

I have visible packet loss that affects everything on my connection (be it my smart TV, streaming, broadcasting, playing video games, VOIP etc.) but isn't detectable by standard means. Speed tests come out fine, ping tests, jitter tests, trace routs, everything comes up fine.

After spending some time trying to figure out the issue, I suspected UDP-specific packet-loss, but I don't really know how to confirm my suspicions.
I've found it extremely difficult to explain my problems with ISP tech support, mostly because they only deal with very basic stuff, but I just can't demonstrate the problems to them, they look at the tests and everything looks fine.

It only takes one look at this video I've put together (https://streamable.com/5zqm1) to demonstrate my issue (it's easier to see on 60+Hz monitors, the issue is much more widespread than just CS:GO, but I have no means of visualising it as well as this).
The video shows 3 clips, 1 demonstrating my POV on a 128 tick server (client-side recording), 1 demonstrating my POV on a server-side recording on my home connection, and the last clip demonstrating my POV on a server-side recording at a friends house, on his connection.

On the server-side recording from my connection, you can clearly see the server interprets my client as a stuttery mess (it doesn't stutter when I spectate other players in the same server demo), and on the server-side recording from my friends connection, everything is smooth and stutter-free (not to mention the gameplay felt like I was playing on a totally different game). It's clear that there's something terribly wrong with the way my traffic is getting handled on the way to the servers, and considering my friend lives 6km away, I doubt it's going haywire in some far-flung router owned by some random company (so it's my local infrastructure causing the issue).

Is there any kind of way that I can use the UDP packets function in the pingplotter standard licence to come up with concrete evidence of this 'undetectable' packet-loss? I tried running it on the default UDP settings to 8.8.8.8 for 24 hours, and couldn't see anything unusual.
CS:GO does UDP updates 64 times a second, so the 2.5 second intervals probably don't represent what goes on, but the second I start using the lower intervals everything starts dropping packets from the very 1st hop. I couldn't find much about UDP traffic from this website, but I'm assuming the packet loss is more likely due to websites or servers not liking random UDP traffic rather than my modem/router combo causing issues (as I've replaced the modem once, and the router 4 times)

My ISP isn't really at fault here, they've tried to fix the issue from what they understand, they've laid new cable from the street to my house and installed a new cable mount/ wall plate, and I've replaced all devices and ethernet cords in the house multiple times, but I'm just sick of having to deal with paying 110 dollarydoos a month for worse quality internet than my friends ADSL2+ connection...