Hello,
if you look at the old dadabik documentation, you will find this:
Searching values containing % or _ using the "contains", "starts with" or "ends with" conditions could lead to wrong search results.
Wildcards were never officially supported and the behaviour you described was not intended, at some point (dadabik 8.3) the bug (or maybe from your point of view, the feature) has been fixed and since then % and _ are considered normal characters.
Best,