I don’t think so, all data are on your device and in the one of the other user. No man in the middle. It’s similar to the paleolitic finger protocol (which still can be used after more than 50 years), but military grade encrypted.
Example of the finger protocol write this in your commandline for an message from me:
finger zerush@happynetbox.com









I use imgur rarely, without account. Sharing images in sites like Lemmy, Mastodon, and other ActivityPub sites don’t need an image sharer, images can be uploaded directly or simply with copy paste. Hosting or backup images and any other files with Filen or Koofr, both 10 GB for free and from the EU (Germany and Slovenia)