I see , but huge image will use more space in your IndexedDB, let me increase the mb size.
The change itself is just a constant, but there are several dependencies to consider together.

The real bottleneck isn't disk storage, it is full-screen wallpaper decoding and memory overhead, and backup export. A 12MB JPEG is actually around 6000px wide, which is more than enough for a wallpaper. Those hitting the upper limit are mostly uncompressed PNGs or original photos straight from mobile devices.

Regarding the dependency with the backup feature, backup process encodes each image into base64 and embeds them into a single JSON file, which increases the overall size by about 33%. With the current import limit at 200MB, raising the image size limit when there is a large volume of images could easily overwhelm the system, so this needs to be adjusted in tandem.

Furthermore, if the two ZIP restrictions (12MB per file and 50MB in total) are not synchronized, it will cause an inconsistency where uploading a single image works, but including it in a theme pack gets blocked.

Could we try to change like this ? single Image + zip per file: 12MB → 25MB
Total ZIP Size: 50MB → approx. 100MB
Backup Import: 200MB → (subject to the adjustments above) increase as appropriate or maintain