Cursor Based Pagination for Timestamp field with non-unique values
ORDER BY deadline ASC, id ASC will be "deterministic" (assuming id is the PRIMARY KEY for the table).  And include INDEX(deadline, id).

More discussion of pagination and the evils of OFFSET:  http://mysql.rjweb.org/doc.php/pagination

If there is any chance of adding or deleting rows while the user is paging through the list, items can be skipped or duplicated in the paginated list.  "Remembering where you left off" (see link) solves the problem.  However, it is a little tricky to say &gt; when two columns are involved.