Discrepancy between InsertObject and Insertable

[shoooe]

I have a ts vector column and I'm trying to populate it via a raw sql tag but if I do it directly in an insertInto statement then it compiles correctly:

await db
    .insertInto("entities")
    .values({
        // ...
        searchVector: sql`...`,
    })
.returningAll()
.execute();

but if I extract the values into a variable:

const x: Insertable<Entities> = {
    // ...
    searchVector: sql`...`,
}

then it complains that the expected type for searchVector is string.

I've looked at the code and it seems that for Insertable this is the accepted input:

export type Insertable<R> = DrainOuterGeneric<{
    [K in NonNullableInsertKeys<R>]: InsertType<R[K]>;
} & {
    [K in NullableInsertKeys<R>]?: InsertType<R[K]>;
}>;

while for values the input type is:

export type InsertObject<DB, TB extends keyof DB> = {
    [C in NonNullableInsertKeys<DB[TB]>]: ValueExpression<DB, TB, InsertType<DB[TB][C]>>;
} & {
    [C in NullableInsertKeys<DB[TB]>]?: ValueExpression<DB, TB, InsertType<DB[TB][C]>> | undefined;
};

which apparently accepts raw sql.

I would have expected the two types to be equivalent. Is there a practical reason for not accepting raw sql in Insertable? Or am I missing something?

Thanks ❤️