@ABSYZ,
Aspose.Slides Cloud API creates new presentations with the slide size 720 x 540 while your input presentation has slides with the size 960 x 540. Because the merge is performed into a new presentation, all slides become the same size. You can change the slide size of the target presentation as shown below:
const cloud = require("asposeslidescloud")
const slidesApi = new cloud.SlidesApi("my_client_id", "my_client_key")
const slideProperties = new cloud.SlideProperties()
slideProperties.Width = 960
slideProperties.Height = 540
slideProperties.ScaleType = "EnsureFit"
slidesApi.setSlideProperties("empty.pptx", slideProperties).then((response) => {
//...
})
You can also check the slide size of your presentations using getSlideProperties
method.
API Reference: GetSlideProperties | SetSlideProperties