The Florida statute that governs public employee labor relations issues permits employees to have their public employer deduct union dues. So, I believe DeSantis proposed change would require an amendment of that statute by the legislature. But even with that, I don't see how this could just apply to the teacher's union. It seems to me that it would have to be a uniform change where the rest of the public sector unions (police, fire, etc.) would be unable to collect dues through payroll deductions.