Q: What is the meaning of the status - Transfer window open?

The status “transfer window open” suggests that the editor recommends the transfer of your paper to another journal, most probably under the same publisher. It is a fairly common practice for journal editors to recommend another journal if they feel that your paper is more suited to or matches the scope of the other journal.   If the recommended journal is under the same publisher, the submission is transferred internally once you give your permission.

I’m not sure how the submission system works for this journal, but generally in case of an internal transfer recommendation, you can access a window that provides at least two action options for the author: ‘Agree to transfer’ and ‘Decline to transfer.’ You need to click on whichever option you choose.

I would suggest that you go through the journal that the editor has recommended and then take a decision. If you think that the recommended journal is suitable for your paper, you can accept the transfer request. However, if you have another target journal and want to submit there, you can decline.