Select by varchar column with IN() part in condition and int value returns all rows

Question

Can someone explain me why with that query:

SELECT * FROM `tags` WHERE (tag IN (\'willa-lentza\', 2016))

it return me all rows from tags<

Answer 1

My brief testing does not confirm this behavior.

SELECT 'test' IN ('other-string', 2016) /* returns 0 */

Not just any string should be able to match an integer. Are you sure you haven't changed anything else?