Failed to give full transactions. Some signatures are missing

I am trying fetch all the signatures of a solana token with details. I am using monthly subscription. But Its failed to give full transactions. Some signatures are missing.

async function fetchSignatures(mintAddress, endpoint) {
  const connection = new Connection(endpoint, 'confirmed');
  let allSignatures = [];
  let beforeSignature = null;
  const batchSize = 1000;

  while (true) {
    const signatures = await connection.getSignaturesForAddress(
      new PublicKey(mintAddress),
      { limit: batchSize, before: beforeSignature }

    if (signatures.length === 0) break;

    allSignatures = allSignatures.concat(signatures);
    beforeSignature = signatures[signatures.length - 1].signature;

    console.log(`Fetched ${signatures.length} signatures, total so far: ${allSignatures.length}`);