Hey Your_average_minecrafter,
There is a file size limit when uploading images, I think it's 2MB. The images are uploaded to Imgur and the size limit comes from their end, so I can't increase it. However, you can post larger images if you upload the image somewhere else and embed it in your post.
With the "Rich Text Mode" toggle enabled, you can do that by pressing the "Add an image" button and filling out the link and title.
![Image description](https://i.imgur.com/TL4qMRy.png)
With Rich Text Mode disabled, you can write markdown like this:
![alt text goes here](https://example.com/large-image.png)
Ironically, this works even if you upload the image to Imgur. For some reason they have higher file size limits for personal accounts than for the API.
Hope this helps!