My Controller Microphone Is So Quiet Nobody Can Hear Me

Both things are true here, which is why this gets confusing. The built-in mic is modest by design, and your specific symptom also suggests something fixable.

The DualSense microphone array sits behind two small ports on the bottom edge of the controller, below the PlayStation logo. It is designed for a controller held at normal playing distance, which is maybe fifty centimetres from your mouth, and it applies noise suppression to keep your room out of the chat. That combination means it will never sound like a headset mic, and if your expectation is headset quality you will be disappointed whatever you do.

But quiet and muffled together, needing the controller close to your mouth to register, points at blocked ports. Those openings are small, they face downward, and they collect dust and lint from hands and from being put down on soft surfaces. A partially blocked port both attenuates the level and dulls the high frequencies, which is exactly the muffled quality your friends are describing. This is by far the most common cause and it is free to fix: a dry soft brush, and compressed air held at an angle rather than straight in.

After cleaning, check the level settings, because there are two places they live. On a PS5 the microphone input level is a slider in the sound settings and it is not at maximum by default. In a browser, your operating system has its own input level for the device plus a possible boost setting. Either can leave you quiet with a perfectly healthy mic.

If it is still weak after cleaning and with levels raised, the mic array is part of the board assembly on this controller, so it is not a cheap individual part. At that point the honest recommendation is a headset or a desk mic rather than a repair, because the cost does not justify it for a component that was never going to be excellent.