尝试一下:

$documentTypes = DocumentType::whereColumn('requester_id', 'protocol.requester_id');
$protocols = Protocol::whereHas('flows', function ($query) use ($documentTypes) {
    $query->where('sequence', 1)
        ->whereHas('documents', function ($query) use ($documentTypes) {
            $query->select(DB::raw('count(distinct document_type_id)'))
                ->whereIn('document_type_id', (clone $documentTypes)->select('id'));
        }, '=', DB::raw('('.(clone $documentTypes)->selectRaw('count(*)')->toSql().')'));
})->get();