I've created one process(deleting chatter post) using process builder. The criteria is created and every time edited. Now the chatter post is deleted for all records. Total 15k records we have in our org. The process builder should fire when condition met.I couldn't find why it fired for all records. Org refreshed. could it happened due to org refreshed. will all records update due to org refreshed.
Process Builders cannot delete records on their own. They can call two tools that can delete records: Flows Apex
If you are calling a Flow from your Process Builder, check to see how you are querying related Chatter Posts. Make sure to filter based on the Parent Record for the Chatter Post. This will happen in a "Fast Lookup" element.
If you are calling an Apex Class or Apex Trigger, your query would also need to be checked, but usually, you can only get Chatter Posts by filtering by the parent record.