Probably just happens to me but that’s why I switched to lemmy.world 5 minutes after I registered my account on lemm.ee.
Yeah the size is frustrating. I asked for an easy way to find image upload limits on my home instance and was met with thunderous silence. I had to keep compressing further and further until I finally found a size it liked.
What was more frustrating for me was the fact that the size limit isn’t reported anywhere (not anywhere obvious, anyway) and that Jerboa did not cleanly handle the error, so I had to eventually retry on desktop to realize it was an image size issue. Neither of these things are lemm.ee’s fault
As a web developer, I can appreciate being hesitant about hosting images, for a brand new service that probably currently exists on just one server somewhere. Text is miniscule when it comes to size, but images can balloon quickly, and I don’t know what the protocol would be (if any) for a Lemmy instance to delete images to reclaim space, in a way that wouldn’t cause problems.
If you have issues with images not uploading consider using a 3rd party service to host your images instead of your Lemmy instance.
I just upload my images and videos to Catbox.moe and use the direct link it gives me to post my memes and videos I share. Also doing this with your images helps save server resources on the Lemmy servers.