Behavior of Tab in a form

Is there a case where it makes sense to use Tab to trigger a search with a long form of search criteria?

I work on complex applications in the medical field and the dev team wants to go from hitting Tab between each field and the option of Enter in any of them to using Tab to Search after the fields that they feel are most important.

So in this example, there are about 15 different search criteria. The user can hit Tab to move between and Enter on any of them to submit the search. They want to switch to search on Tab for 2 of the 15 fields.

The reasoning is the devs observed users in a launch struggling to understand that they had to hit Enter or the Search button in the footer. The users came from using a very old application that did not use this modern-day concept and needed time to adjust and catch up.

I would love to hear thoughts on this.