Stuck tab input - Cannot Command-Tab switcher, and more errors

I have a nagging issue which is my iMac is repeatedly stalling out opening and completing tasks, and now I cannot use a basic function—the Command-Tab Application Switcher—because the tab key doesn't work. I try it and the focus ring cycles backwards to the frontmost app, without any further input on my part.

Oddly, another app that is being affected is Minecraft, where the hot bar is constantly cycling through the tools, without my input.

I can't find out what is causing the input. My keyboard is otherwise functional and the Tab key is not stuck, so I figure there is some kind of stuck input happening from… somewhere. And I can't track it down.

Nothing else I have tried works. I have removed third-party USB devices, restarted in Safe Boot mode, reset my NVRAM, updated to the latest version of Sonoma, tried adjusting keyboard settings, logging in and out of iCloud services, and more. The problem keeps recurring, and I can't find more help about this issue online.

I tried looking at the Console logs, and while it's filled with a constant flood of errors every second, the messages are like a foreign language to me. there are multiple invisible processes spewing out errors.

I don't know what else to do, and I don't have another Mac I can work on. Please help!