SEVERE INTERACE PROBLEMS IN VENTURA

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac, run for a while and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

IS… about that bigger monitor of you. I'm interested. Which one is it

My “monitor” is a 43” UHD TV, Visio, I think. There isn’t a mic nor a camera.

I don’t have any control over the volume from the Mac. I have to use the TV remote. So, no Bluetooth involved.

Are you using Apple Magic Keyboard / Mouse or a 3rd party bluetooth KB/Mouse?

Do you have an external drive attached? Any other electrical devices near your M2 Mac Mini?

It sounds like bluetooth interference which can come from an external drive or other device putting out EMF (Electro-Magnetic Field) such as a fan motor, radio transmitter, the monitor itself, etc. It doesn't take much to disrupt bluetooth wireless signals.

If there is an external drive attached, try moving it as far away from the M2 Mac Mini and your KB/Mouse as you can. If it uses a cable that is not hardwired, you may be able to source a longer cable enabling the drive to be moved further away.

If it's a third party bluetooth KB/mouse such as Logitech MX, it would be better to use the wireless transceiver USB plug instead of bluetooth. It will have better range and reliability over bluetooth.

I can’t imagine I’m the only one being disturbed by such an inadequate automatic scrolling.

You are assuming many others experience the same thing. Perhaps they are not disturbed by it because they don't experience the same problems.

I have an M1 Mini with Apple Wireless TouchID keyboard and original Magic Trackpad (and an even bigger monitor). I also have an M2 MacBook Pro. I have never seen anything like that on either Mac (nor on my previous Intel Macs).

To make it complete: sometimes the current window trembles; i.e. it moves 5x up and down with an amplitude of around 20 pixels.

And to give a second example: when I’m entering a search in Google, upon hitting the return key, the whole screen (¡but NOT always!) scrolls to below the second or third answer Google provides. So just to view the first one, I’ve first to scroll upwards!

2/2. SOUND INCREASEs TO ITS MAX

When I’m listening to music (a) via standard app Music = ex-iTunes or (b) another app (like VLC to watch a movie), and I want (a) to click a song (for whatever reason) or (b) go to another part of the movie, the audio volume suddenly increases to its max (I’ve 2 little but very good loudspeakers), thus almost damaging my eardrums and disturbing (heavily) my neighbours.

These 2 interface problems happen randomly. After 222 days, I still haven’t a clue what causes this very disturbing behaviour. 

For the SOUND problem I’m just using the mouse, for the VISUAL problem I’m (mostly) only using the keyboard.

Based on your troubleshooting and these symptoms, I would say you have some hardware problems. It could be in the peripherals (if you have wired keyboard and mouse you could eliminate those from the analysis).

I would contact Apple Support and set up an appointment with an Apple Store Genius Bar or Authorized Repair Center.

The Magic Mouse is very sensitive and even coming close to touching (hovering) where the scroll wheel would normally be situated can engage the scroll and also introduce inertia. Then you start a scroll but move the mouse and the scrolling inertia carries over and lands on a new window and it can be annoying. It's quite possible this is the root cause of your problems.

Try turning off the inertia feature. In System Settings search for 'inertia' and there should be an option to turn it off. It's buried under accessibility options. Be aware of how you hold the mouse and where you position your fingers. Some people absolutely love the Magic Mouse and others despise it. By no means are you restricted from only using Apple peripherals. Most any KB/Mouse will work with Macs.

I would avoid gaming products with many buttons and RGB lighting. They typically require software that is not available for macOS. Ironically, I had a user today whose Microsoft Teams kept crashing and it was due to a Roccat Leadr gaming mouse which was using no software. I personally love the Logitech MX Series for Mac.

There are 3rd party software tools that give you a lot more control over the mouse and keyboard, etc. BetterTouchTool is among the best.

Nobody here can answer those questions. If you want to know the answer to why anything on Apple works the way it does you’re gonna have to talk to Apple support.

Make sure you update to the latest macOS Ventura 13.4. There was a bluetooth fix included.