
The default width / height of images inserted in rich text is 224px maximum.
If the original image stored in Keepeek have a bigger size, you can improve this default width. Just press the "Advanced" button in the "Insert image" window and grow the value (ensure the "Proportion" option is thicked).
The image is going to be degraded in Edit mode, but continue your edition, Finish the editing and you will see in Staging that your image have now a better resolution.
Explanation: the Edit mode works with images reduced a lot to improve the bandwidth consumption. But is you improve the size, the Staging (and Live) is asking to Keepeek a better sized image.
Note: To access this "Insert image" window from an ever added image, you must select the image (click beside, then highlight it), the press "Insert" > "Image", as if you wanted to insert a new image. Only the image have to be selected (nor space, nor any other character).