It might be really upsetting if your Reels start off in excellent resolution before blurring within a month or less. However, there can be a few causes for this problem. Let's examine some potential outcomes:
To begin with, it's conceivable that Instagram is compressing the videos to save server space usage or speed up download. Blurring can occasionally occur as a result of this compression since it lowers the video quality.
Your internet connection is another thing to take into account. Although you said that your connection was robust, it's important to keep in mind that network conditions might change. The video quality may suffer if network congestion occurs or if your internet speed lowers during uploading.
Last but not least, remember that Instagram is constantly changing its features and algorithms. The quality of your Reels can degrade over time as the platform's encoding or processing techniques evolve.
You could test a few different things to figure out the problem. First, make sure you're still utilising the right ratio and video quality settings by double-checking your upload settings. Additionally, you might want to test submitting the Reels on other days or at various times to see whether that affects the quality.
It's worth contacting Instagram support if the issue continues and has a substantial impact on the viewing experience to see if they can offer any more assistance or insight into the situation.