[heavenlyblue]

Unless the database is also encrypted and provides the same homomorphism against reverse index queries.

[betterunix2]

In which case you are no longer talking about FHE. With FHE the server receives a ciphertext query and produces a ciphertext output, without ever seeing any plaintexts (not even the result of a reverse index query).

[soberhoff]

If the database was encrypted, you would need a different encrypted database for every user - again impractical.