If you are experiencing an issue where only one speaker is working on your iPhone XR, it is important to determine the cause of the problem in order to fix it. Here are a few potential explanations for why only one speaker may be working on your iPhone XR:

1. Physical damage: If the speaker in question has been damaged in some way, it may not be functioning properly. This could be due to a drop or impact, water damage, or another form of physical damage. In these cases, it may be necessary to repair or replace the speaker in order to fix the issue.
2. Software issue: If the speaker is not functioning properly due to a software issue, it may be possible to fix the problem by resetting the device or updating the operating system. It is also possible that a third-party app or feature may be causing the issue, in which case uninstalling or disabling it may resolve the problem.
3. Hardware issue: If the speaker is not functioning properly due to a hardware issue, it may be necessary to repair or replace the device in order to fix the problem. Hardware issues can be caused by a variety of factors, including age, wear and tear, and manufacturing defects.

If you are unable to determine the cause of the issue or are unable to fix it on your own, it may be necessary to seek the help of a professional. Apple’s customer support team or an authorized service provider can help you diagnose and fix the problem.

Regardless of the specific cause of the issue, it is important to address it as soon as possible in order to ensure that your iPhone XR is functioning properly. If you are experiencing any other issues or abnormalities with your device, it is a good idea to take it to a professional for evaluation and repair.