Google writes the same number to localstorage, what does it mean?

Question

Google

Hello.
When visiting google.com, an entry appears in the browser's local storage (Firefox) with the key og-up-OGPL . The value is a seven-digit number. After deleting the record, when you re-enter, it again records the same number.

• What does this number mean?
  
• And how can I disable writing to localstorage for a specific site?
  

UPD Just answer, do you have this too?