File Storage for Web Applications during production

Which form of file system SQL, NoSQL, the cloud, or a static/subdirectory inside the application should I use for my web application?

sql: I've tried to save the images as blobs, but I can't get them out and display them on the flask application.

Cloud storage: I successfully built an S3 bucket, placed a file there, and am now able to view website images. I attempted to deploy the website on ec2, with the aws id and secret key properly specified in the configure file. My s3 bucket is public, however my nginx server reports a "502 bad gateway" (in localhost it works fine).

File system: Storing an application's images within a folder and its metadata in a mysql database. This method functions without any problems, but the question is whether it will result in more photographs being kept in the folder as the application ages, say, if I want to keep the images for a longer period of time.

1. Does it cause a server stess?
2. Is this way of saving the images effectively?
3. Does it slow down the application process over time as no of images increases?
4. What additional issues can I encounter as a result of this process?