Why MacBookPro mds_stores disk write so big?

It is caused by Spotlight and the only way I found to stop it is to switch off Spotlight.

Open System settings/Spotlight and scroll to the bottom where you will find a button called "Search Privacy".

Click it and in the window that opens add all your drives.

That will immediately stop those huge writes which incidentally never appeared on the drive . . . it's as though they were instantly deleted the moment they were written.

You can use Find Any File to search for files and content, it actually is a superior search tool. Meanwhile, you can turn off Spotlight temporarily while troubleshooting.

To possibly find out the root cause for your mds issue, you can download Etrecheck and run it, and post its report here as described here:

Using EtreCheck to Troubleshoot Potential… - Apple Community

Etrecheck's report does not include any personal information but it does describe the computer setup and from that the cause can be identified sometimes.

Disable Spotlight as I explained in my first post.

Follow my instructions to turn off Spotlight and it will stop.

There are other search apps like EasyFind that do not cause this problem.

Try updating to Tahoe to see if it stops the problem.

What about

Configuration profiles found - This computer may have configuration profiles installed.