After having imported multiple issues from an excel into a JIRA project (cloud) we are facing a problem with the auto generated numbering (issue key). We set the numbering manually per our wish (for all the imported issues) and the last issue took the number 103. When we tried to create( Create c) a new issue in this project, we realised that the newly created issue took the number 407.

Could you please advise us why this is happening? Can we solve it somehow?
We would like to keep the sequence we have already set. It was expected to add/create a new issue and the issue key number should be 104 (instead of 407), if i am not mistaken.
Thank you in advance!