This is the message they are sending to users:
Hey u/username,
We will soon begin rolling out changes to Reddit's User settings. It is getting a refresh that includes changes to ad personalization, privacy preferences, and location settings.
As part of these changes, we are retiring a setting that you have previously turned on that limited how we used your activity from the Reddit platform to personalize ads. We have replaced the setting with a new option to select categories of ads that you may not wish to see.
More details are available in our announcement and help center.
These changes are rolling out starting today and you may see the changes over the next few days.