license - proprietary code not under MIT included?

[HSH73]

The file https://github.com/facebookexperimental/Recoil/blob/main/packages/recoil/hooks/Recoil_useGetRecoilValueInfo.js contains the line "(c) Meta Platforms, Inc. and affiliates. Confidential and proprietary." This was flagged in our foss compliance scaning process as proprietary license info.
The other files in the same folder (https://github.com/facebookexperimental/Recoil/tree/main/packages/recoil/hooks/__tests__) are marked only with "Copyright (c) Meta Platforms, Inc. and affiliates_." and an explicit reference to the application of the MIT license (see for instance https://github.com/facebookexperimental/Recoil/blob/main/packages/recoil/hooks/__tests__/Recoil_useRecoilSnapshot-test.js.
Must the reference "Confidential and proprietary" and the missing reference to the MIT license be understood as if this specific file is not subject to the MIT license governing the overall project? If not, I suggest to change the info. The reference "confidential" is obvioulsy already incorrect given it is published on github.