Voice memo - 2 hours

Here is an example of an external voice recording on my iPhone 12 Pro. Please see the comparison below

Same Song, environment, device, length of recording

• Compressed Format Recording: 502 KB: This is the default setting and offers a good balance between audio quality and file size. A 2-hour recording in this format would likely use around 500 MB to 1 GB of storage.
• Lossless Format Recording: 2.8 MB: This format preserves all audio details and offers the best quality, but it also uses significantly more storage. A 2-hour lossless recording could use up to 3 GB or more.

You may get better and prompt responses if you may kindly provide the iPhone Model that you have and the iOS version if it is known to you and re-post.

With the limited information that you have provided, It is hard to even guess the problems faced by you.