Mac Mini M4 (brand new) input lag

That sounds like RF interference - replace your monitor.

Sounds like BT interference. What else is connected? Which year was the mouse manufactured? If it isn’t late model Magic 2, I’d replace with a new Trackpad - works both wired and wireless and switches automatically.

It sure has. I have multiple Mac Mini’s including the M1 and it did that from the time I bought it. Sometimes it’s fine and other times it’s awful to the point of being unusable and I switch to a wired keyboard.

That’s your experience, not one that “has plagued all the Mac Mini’s since the M1.”

Start a fresh discussion if you’re interested in troubleshooting your issues, otherwise please refrain from sweeping generalizations that are essentially unverifiable i.e. false - not helpful. Use Reddit or MacRumors for that.

I am told that apple silicon needs the Magic Keyboard with Touch ID or there will be some apps that do not work well or at all. Magic Trackpad seems OK. "magic" items that work well with OS15.2 on Intel may not work with OS15.2 on Apple silicon - go figure.

You need to check the mouse settings on both computers in System Settings as tbirdvet suggested.

Each mouse you use will need different settings on each computer.

If it isn’t late model Magic 2, I’d replace with a new Trackpad - works both wired and wireless and switches automatically.

Check your mouse settings in preferences and try to adjust some of the settings.

Same here. I have regular m4 and it works great, but the m4 pro has a lag. I'm using the same wired mouse on both to evaluate.

That sounds like a load of "RF". Don't blame it on the monitor. This has plagued all the Mac Mini's since the M1.

Nope. “This” has not.

That’s not my experience at all. What is “I am told””? Be aware that speculation and rumors is not allowed here.