iterMessages nor getMessages can retrieve more than ~15000 messages at once

[1982FenceHopper]

I'm trying to retrieve almost 80000 messages from a Telegram channel, but it only gets around 15000. I used offsetId to try and retrieve more older ones and it works, but it only retrieves around ~100-200 messages after. I can't keep modifying the offsetId as that would be extremely tedious with around 60000 messages to go.

My code so far

export async function Telegram_DRI(
  canonical_identifier: string,
  limit: number // Ignored variable for debugging
) {
  const client = TelegramServiceClient.getInstance(); // Singleton class I set up.

  let manifest: TotalList<Api.Message> = [];

  try {
    await client.connect();

    const user = await client.getEntity(canonical_identifier);

    for await (const message of client.iterMessages(user, {
      limit: undefined,
      offsetId: 65050, // !!! I keep having to modify this to get older messages, and it still only returns ~100-200 messages each time
    })) {
      clc.log(
        `-- FOUND MESSAGE ${message.id} FROM AUTHOR ${
          message.postAuthor
        } OF LENGTH ${message.text.length} WITH MEDIA ${
          message.media ? "AVAILABLE" : "NOT AVAILABLE"
        } --`,
        ANSI_COLORS.BRIGHT_WHITE
      );
      manifest.push(message);
    }
  } catch (e: any) {
    clc.log(e, ANSI_COLORS.RED);
  } finally {
    await client.destroy();
  }

  return manifest;
}

I am logged into my Telegram account rather than using a bot token.