When you upload a file into the CRM, the file is stored in data/uploads, so it is only available to the instance that uploaded it unless you are sharing the uploads directory between docker instances. This is a functionality problem.
If the files are stored in S3 or shared between instances by the docker host, then it's probably fine, but it's not clear how it's being handled. If one instance uploads a file, it will be shown in the GUI to all instances even if the file isn't available because the filename and link are from the database, not the disk.