That's specifically an issue because of how different individuals (teaching staff) understand and communicate anything to do with the concept of transgender.
If there was a hard party line on how to communicate it in schools and at what age, it wouldn't be an issue.
Need to bare in mind that schools all read each others reports and set up action plans. Heads talk and share experiences with Ofsted. Teachers are tasked with diversifying the curriculum. In primary, Teachers have a subject area. These days most of them write the content.
I've seen classroom teachers (not senior leaders) asking for ideas of how to include transgender in eyfs and ks1 in individual foundation subjects.
The easiest way, and kills two birds with one stone, is via books. Ofsted are obsessed with reading and how the school floods kids with books and reading.