So she shared info about the child in a confidential meeting with solicitors as part of obtaining legal advice? Perfectly normal and no harm done. Any info shared is kept confidential under legal privilege. The solicitors won’t be leaking it to the local press.
The child’s trans status has already been publicised, by themselves and others, as they have been socially transitioned. Everyone in that school knows they used to be know by one set of pronouns and name and now they wish to be referred to by another name and the pronouns used for the opposite sex. Everyone knows they are actually one sex but want to present and be treated as the other.
This is quite clearly just an excuse to sack the teacher. A hook to hang the sacking on, that they’d already decided on. Hopefully a tribunal will have the nous to see through it.