Imgur now blocks several VPNs and have issues loading embedded previews in several fediverse platforms. So instead of using imgur, you could use one of the following alternatives for uploading your images.
https://postimages.org/
https://imgbox.com/
https://imgbb.com/
https://www.imagebam.com/
Using them do add one or two extra steps before posting. Images can hog up server resources and using these third-party sites reduces the burden for the server of your instance which is run by volunteers/hobbyists with money often coming from their own pockets. Its just a nice thing to voluntarily do.
On the other hand, it’s great that some instances have file size limits. It forces users to look at these image hosts instead of them just recklessly uploading images into the servers as if Lemmy is housed in a Palo Alto facility.