HELP, MBP 2015 13", I might have tried every possible solution in existence

[robustpotatoes]

Hey everyone, asking for help on a first post seems like a terrible way to say hello to the community but I am actually pretty desperate right now so I hope it's okay!

I have been using a 2015 13" MacBook Pro (running Monterey at the moment) with 3.1 GHz i7 processor with integrated graphics, 16 GB RAM, and 500 GB SSD since July after upgrading from a MacBook Air which I was using for the last 6 years. (never been a fan of the next generation of MBP, plus I am broke haha)

I work in research, so I do pretty extensive simulations for statistical analysis, coding, web-automation and also music production, so having 16 GB of RAM and an old i7 is more than enough for the most part. Anything related to visual content or graphics is almost non-existent in my daily routine (apart from browsing). The moment I bought the laptop (previous user only used it for Office and web browsing), I took it to an authorised service and got thermal paste re-applied and interior cleaned. I did a clean install and didn't use a Time Machine backup, no migration assistant, just slow but fail-safe manual labor.

I highly suspect that there is somethign related to the GPU of this laptop and here are some instances when I will see my CPU use skyrocket and my fans running at max capacity (fyi, my base spec 4 GB RAM Air had none of these issues):

1. Anything that uses my webcam, fans and CPU load goes CRAZY. (Safari, FaceTime, Skype, Teams, Zoom, browser live chat, you name it)
2. If I try to watch a video with the quicklook feature, fans run up to 5000 rpm instantly
3. Plugging an rather old external monitor (a DELL from 2015) makes my fans run at 3000 rpm idle.
4. Watching a live conference via Safari, without using mic nor webcam, same problems.
5. Under all of these cases, I never see my GPU fully utilised whereas CPU reaches its limits. (see iStat screenshots attached)
6. Bonus: infamous screen flickering on Safari during fullscreen
7. According to my tests, for the CPU, even under maximum load, there is no throttling whereas for GPU I see up to 30%-50% loss.

During these months, I have been spending hours each week trying to figure this problem out and apart from this, I am pretty satisfied with this laptop. At this point, I've done countless EtreChecks, used tools of ObjectiveSee, removals of anything unnecessary, re-installs, log reports, diagnostics (never ever got a problem), SMC resets, different OS versions, pretty much anything you can imagine.

At this point, I am pretty desperate and would appreciate any kind of recommendations. Thanks a TON in advance!