Bizarre macOS Browser Problem

I have encountered a rather bizarre macOS problem and I'm wondering if anyone else has seen this in the wild, or has any ideas on how to mitigate it. I've been a Mac admin for a very long time, and I've never before seen anything quite like this. **The Problem**: Very simply, on certain random websites, the helper/render agent of EVERY web browser immediately goes crazy, reaching and indefinitely remaining at 100% CPU or higher. **When First Observed**: Approximately January 2024 **What I've Tried**: - **Clean browser profiles** (this includes no browsing data, no extensions, etc.) - **Fully Uninstall/reinstall browsers** (except Safari, of course) - **Different browsers** (I've tried Safari, Edge, Brave, Chrome and Firefox) - **Different macOS versions** (I've reproduced this on macOS 11 [intel], macOS 12 [M2], macOS 14 [M2]) - **Different user accounts** (I even created a new one just to see what would happen, and there was no difference in the behavior) - **Different machines** (I've used an M2 MacBook Air, M2 Pro Mac Mini and 2019 16-inch MacBook Pro) - **Safe Boot** (This one shocked me, but even in Safe Boot with only essential macOS processes running, the behavior is still exactly the same) - **Clean macOS installs** - **All of the standard things not listed above which can be found on every blog** (disable hardware acceleration, change random setting X, Y or Z, etc.) You would think that all of the above would have led to at least some different combination of results, but literally nothing changed. For instance, the M2 Pro Mac Mini is a brand new machine and it does this straight out the box. Based on these variables and results, I can only conclude that this is something within macOS itself. It is clearly not isolated to a particular browser, browning profile, user account, machine or OS. We know that Edge, Brave and Chrome are essentially using the same Chromium engine, and thus have similar backend processes. It would therefore be logical to assume that if there's some kind of Chromium-based reactivity somewhere within macOS, they'd all display similar behavior. Yet, we see the same behavior on exactly the same websites with Firefox and Safari, two browsers with totally different engines and codebases. It could be something about how the operating system handles these rendering processes, but what could that be and how could it be corrected? I've attached screenshots of the runaway render processes in Edge, Firefox, Brave and Safari. Has anyone else observed this? Please let me know if you have any ideas or there's something I haven't thought of. Thanks for your help!