PS CC 2019导出Web所用格式遇到BUG？

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First of all, my image 648x150px is divided into three equal parts by the reference line, and then the slice is created based on the reference line. Now the image is required to have a sum of image sizes of no more than 100kb, so when I export the format used by the Web, I chose these three. Slices were made and the image quality was adjusted to meet the total size of less than 100 KB. This step is done, I saved the source file. Next, I open the source file again, now I want to save this image as a piece, no need to slice, use the slice selection tool, I deleted the slice. I did this in the previous version, and there was no problem. Now, the trouble is up. Question 1: I export the format used by the Web again. The panel image is semi-transparent and has a blue box. Clicking on the image shows the unselected slice on the right. Why? Question 2: After the problem 1 occurs, although the slice is not selected, it can be saved, but the image saved on this computer is not a high-quality image, and it is obviously compressed. Why?