Year-old workflow suddenly adding new rows to the top of Google Sheet as of 2 days ago, instead of bottom

Year-old workflow is suddenly adding new rows to the top of Google Sheet as of 2 days ago, instead of adding new data to first blank row below my data (which is what we expect).

We want to revert this behavior, and restore the ability to add new data to the bottom of the Google Sheet.

AFAIK, the workflow hadn't been touched in over a year.

Please advise.

Possible reasons for this:
1. Any blank row created on top or any blank row in between the rows?
2. The headers of the sheet are changed, moved in any way.
3. Any 2 columns merged?

These are the possible reason for this issue.