You've posted a litany of woes, but since this is a user to user forum (not user to Apple), the best approach is to post with one specific issue and see if the thousands of users here have seen that before and how they resolved it, sort of crowd sourcing your query or problem. It's sort of hard for other users to try to address your many other complaints ranging from Macs to iPads to Apple support contact issues, or something about a Genius Bar person you did not like.
I think you got some good suggestions from experienced people here about ridding your computer of extra "system management tools" you may have installed. Items do load that are not listed in your login section. Many typically have extensions loading and operating even when the app is closed. On both Macs and PC, the OS has come leaps and bounds over the old days when little utilities could tune things up or improve them and they now mostly do not help and can do harm. Especially with the latest MacOS like Big Sur or Monterey, definitely would not "tweak" those; many of those utilities or hacks were written years ago and don't interact well with the modern memory or disk management built in features of the MacOS. I would remove them all and see how things go. I usually start with Occam's Razor which says the simplest solutions are mostly likely to be the ones to try first. I see many stock machines in Apple Stores running very fast and responsively. Why not try to restore the OS back to something close to how it came from Apple and see if the issues go away.
Facebook can be insidious and you might explore your settings carefully to see what you have allowed there. Depending on what you do on Facebook, there could be background videos trying to play constantly through your connections. Other web sites can cause great slowdowns differently on various browsers, some on Safari, some on Firefox, some on Chrome.
Several other items I noticed:
(1) You appear to have a fusion drive from 2017. Those fusion drives have sometimes proved to be problematic, in part because they mostly depend on a slower mechanical (rotating) drive. If Disk Utility can check the file system on that drive, I would do that, and/or use a tool like DriveDx (extended, long test) for its hardware.
(2) Malwarebytes -- a good program to detect malware, but some have reported that having its background checker running all the time has slowed down their system's responsiveness. Others don't seem to see that. So you could TRY simply turning off the background check function of Malwarebytes, reboot, and see if that helps. It will still check everything upon login or with scheduled or manual scans.
