Hello robdejonge,
Adjusting the microphone access for that particular website in the Safari settings should have addressed that behavior: Change Websites settings in Safari on Mac - Apple Support Let's take some additional steps to help isolate that further.
Let's use the steps below to make sure that your Mac is up to date: Update macOS on Mac - Apple Support
1. Before installing new software, it's a good idea to back up your Mac. If you have an external storage device, you can use it to back up your Mac with Time Machine.
2. To check for new software, open Software Update:
• From the Apple menu in the corner of your screen, choose System Settings. Click General in the sidebar, then click Software Update on the right.
• Or in earlier versions of macOS, choose Apple menu > System Preferences, then click Software Update.
3. If Software Update finds new software, click the Update or Upgrade button to download and install it. You will be asked to enter your administrator password, which is the password you use to log in to your Mac. During installation, your Mac might show a progress bar or blank screen several times.
If Software Update says that your Mac is up to date, then no new software is currently available for your Mac model. Software Update shows only software that is compatible with your Mac.
Updating can sometimes help address odd behaviors.
If your Mac is all up to date, let's use the applicable set of steps below to boot into safe mode to see if that persists from there: Use safe mode on your Mac - Apple Support
If you're using a Mac with Apple silicon
1. Shut down your Mac.
2. Press and hold the power button on your Mac. As you continue to hold the power button, your Mac turns on and loads startup options. When you see Options, release the power button.
3. Select your startup disk. It's named Macintosh HD, unless you changed its name.
4. Press and hold the Shift key, then click the “Continue in Safe Mode” button below your startup disk.
5. Log in to your Mac. You might be asked to log in again.
If you're using an Intel-based Mac
If you're not using a Mac with Apple silicon, you're using an Intel-based Mac.
1. Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up.
2. Release the key when you see the login window, then log in to your Mac.
3. You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window. If you can't start up in safe mode, make sure that your Mac isn't using a firmware password.
It can take a few extra minutes to boot into safe mode. Your screen may flash or flicker while in safe mode. Those behaviors are expected. Testing in safe mode runs a check on your disk, removes some cached files, and can help isolate conflicts with startup items. Once you've tested that behavior in safe mode, you can restart to leave safe mode.
Let us know your results, and we'll keep moving forward from there.