Hi @Aras,
Materials Project’s database is updated several times a year with new calculations and methods, see here for example.
To see the current database version, you can see it in the footer of every page on the next-gen website (v2021.11.10 at time of writing) or on the “citing” page on the legacy website (v2020.09.08 at time of writing).
The difference in these values is because next-gen is running on a newer database version; the legacy website will be frozen on database version v2020.09.08.
As you noted, the anion correction is the same for both, but the uncorrected energy is different on the next-gen website, suggesting that in the most recent database an alternative calculation was selected as being higher-quality and the energy from that calculation was used instead.
Hope this helps,
Matt