Brightness and sound dialogue box don’t react to my input on MacBook Pro running macOS Sequoia

Shall leaving the below for the User to ruminate upon

There are 4 Categories of Third Party Software / Services that are baffling.

Why some users insist on installing and using the below software. 

In no special order 

Third Party 2 Way Firewalls 

like Lulu and Little Snitch 

Commercial VPNs 

They may not be what one believes they are doing for the computer and what they actually are doing behind the scenes They may also reduce you Internet Speeds by upwards of 30% 

https://gist.github.com/joepie91/5a9909939e6ce7d09e29

VPN: What you need to know - Apple Community

Third Party Security Software 

There are no known Windows-like Viruses in the wild that self replicate and affect macOS, because of the underling UNIX  Foundation and Permission Limitation. 

The Operating System resides in a Sealed and Read Only Volume that cannot be opened by the User nor by Third Party Applications.

The Only thing this Antivirus software is protecting is the Bank Account of the Developers and for zero return to the User aside from the problems this software creates.

Security. Built right in

Mac app security enhancements

The Built in Security  is all that is required to protect the computer.

Protecting against malware in macOS

Third Party Disk Cleaners / Optimizer 

Any Third Party Applications that will interfere with the normal operation of the OS,  is an invitation for disaster. 

Certain Applications maybe available on the Apple Apps Store - this only means the Developer is prepared to pay Apple a percentage on each sale. 

What the Application may do to the computer is up to the User to check this out before purchase

To put the Third Party Disk Cleaner / Optimizer in context and the damages it may have or has already done.

This type of applications can or will Muck Up your User Account ( Home Folder ) of this machine.

It does not touch the Operating System itself unless you consider your User Account ( Home Folder ) as part of the Operating System.

The Operating System is hosed

Any of the below should be removed as per Developers Instructions 

Disk Cleaner 

CleanMyMac , aka “ BrickMyMac “

New macOS Malware "Cthulhu Stealer" Targets Apple Users' Data

Un-Like Microsoft Windows, which does have “ Disk Cleanup “ and “ Defrag “ as part of their Operating System 

Apple does not  

It surely is no coincidence that both macs show the same problem. Also the fact that it works in Safe Mode offers further confirmation that the problem is probably caused by some third party software that was migrated to both.

I recommend that you post the Etrecheck report, as others may notice something that you may not have deemed relevant. Use the “additional text” button and paste the full report into the text box.

OUCH!!!!!

[Running] com.macpaw.CleanMyMac5.Agent.plist (MacPaw Way Ltd - installed 2025-07-14)

You should never ever ever install such ****

This is known around here as "brickmymac" and with good reason.

How about doing an Apple Diagnoses

To run it, shut down your Mac, then power it back on while holding down the "D" key

I ask only because as you mentioned if worked - sort of ) in Safe mode

As we know, such functionality for the Sound and Brightness controls as per your images

They are Hardwired from within the SMC or NVRAM

Therefore, Safe Mode works, sounds ( no pun intended) really really abnormal at best

Start by >> Reset NVRAM on your Mac

Perform this action 3x consecutively

Still issues ?

Reset the SMC of your Mac

Also, Perform this action 3x consecutively

I concur with the assessment by @ Luis Sequeira1 👍

Post back the Full Report - Share Report >> Copy , then  paste  >>>> using the Additional Text Icon  <<<<

Nonetheless, from whichever of the 3 different reports from Etrecheck we have looked at or work from.

If the iBridge software, which I believe, is associated with the T2 Chip, has become corrupted / damaged in some way

The functionality of the Sound and Brightness controls that are Hardwired, may not function to the users expectations or how they should function

How to fix the iBridge software may require to Trip to your location Genius Bar or perhaps.

Have the computer evaluated by the Professionals who have the Special Hardware Software and Expertise to diagnose the issue and offer possible solutions

You are welcome

Though, this machine is performing well below the expected values

Runtime: 7:27

Performance: Below Average

Apple Inc. - Apple T2 Controller

After ALL and I mean All avenues has been explored and exhausted

Last resort

Rarely, a Mac with Apple silicon or the Apple T2 Security Chip might stop responding and need its firmware to be revived or restored by another Mac

A little something I could elsewhere and is directly related to both issue

https://www.macrumors.com/how-to/adjust-mac-volume-brightness-more-precisely/

I could be wrong, but this make and model is known to be not be one of the better machines as a offering from Apple 

Whether Crystalidea macsfancontol  and SSDReporter  come into play as it relates to this issue

I do not know 

MacBook Pro (16-inch, 2019)

MacBook Pro Model: MacBookPro16,1

Performance: Below Average

System modifications - There are a large number of system modifications running in the background.

Low performance - EtreCheck report took an unusually long time to run.

1 -  com.crystalidea.macsfancontrol.smcwrite.plist (Ilya Parniuk - installed 2025-07-08)

2 - SSDReporter 1.6.1