Explain and analyze: because, the general state is from? The change from "under review" to "under decision" means that the review is over and the editor needs to make a decision on the paper. It will become under review again because the editor is not satisfied with the review opinions, so it will be sent to other reviewers again, but the status is unlikely to change within one day, because the editor needs to read the review report first, then find the reviewer, send the review invitation and wait for the reviewer to accept the review.
In addition, strangely, the status changed between "under review" and "under decision" for four consecutive times. I think there may be something wrong with the system. You should send an email to the editor immediately to express your doubts and confirm what the actual state is.
Related events:
Many times, Under Review refers to the external audit of reviewers, and some journals also use it to indicate that editors are auditing internally, which is also the reason why people have the above questions.
Specifically, it can be analyzed by combining the time node and the status of the manuscript before and after. For example, when submitting the next day's Under review, nine times out of ten, it is an editorial internal audit, because it is impossible to find reviewers so quickly.
From assigned to AE under review to evaluation suggestion, because there is no update about reviewers, and the statement of evaluation suggestion is often used in editing. This looks more like a series of internal audits.