It has been a requested feature for a long time: it is now possible to upload images and attach them to expenses.
The most common scenario is uploading a receipt, but the feature can be helpful even to store photos and remember what an expense is about, even long time after it was made.
Technical implementation details: the photo is uploaded to an S3 bucket. When the application is self-hosted/self-deployed, it is possible to either provide an S3 bucket or disable the feature.
Short demo in this LinkedIn post.