Why sortByProfitabilityUsingMaxCover is using maxCover ?

[mitmotw]

https://github.com/prysmaticlabs/prysm/blob/a85b4445fc6dcbc066fa375b0e77befae8b02c8a/beacon-chain/rpc/prysm/v1alpha1/validator/proposer_attestations.go#L148

sortByProfitabilityUsingMaxCover is doing maxCover for the attestations from same slot.
However I guess there might be some attestations from different committee index.
The test codes are not caring about attestations from different committee as well

The whole attestations are guaranteed to be from same committee ?

The proposer is fetching those attestations from the pools,
so I'm not getting how it's guaranteed.

https://github.com/prysmaticlabs/prysm/blob/a85b4445fc6dcbc066fa375b0e77befae8b02c8a/beacon-chain/rpc/prysm/v1alpha1/validator/proposer_attestations.go#L28

Please fix me if I'm wrong. 🙏