Why arXiv version disappeared from Google Scholar profile once journal version published
It doesn't disappeared, it is only grouped together. If you click to your article in Google Scholar, at the end of the page, you'll find "All N versions". Click on it, you will find your ArXiv versions, and some other mirror sites that you may not aware.

Next time, if you want your ArXiv version to be listed separately, change the title to "My awesome paper (extended version)". When the titles are different, the article will not be grouped together.

Note: it's never a good idea to inflate your paper count in Google Scholar with different versions of the same paper.