Personally, I don't mind which pronouns people want to use, it doesn't matter a jot. And young people are much more fluid in their approach to gender, which is fine. But gender and sex are two very different things. Sex is noted at birth, it is not assigned in some arbitrary way. I delivered countless babies in my career as a midwife and I can promise you, I didn't assign any baby to any gender. Biological sex is real, observable and can be proved scientifically. Occasional nature is less sure and babies can be born intersex-but that is very rare and nothing what so ever to do with transgender. Gender is a much more nebulous thing. Based on feelings and sense of identity. Particularly among the young experimenting with who they are and who they want to be. Where it does matter is where clarity is needed. For example sport.
Say you are a young woman with ambitions to cycle professionally. You are good, you train hard. Cycling is your life, your passion. You are one of the best. You are focused, determined, you want to win. You enter the most important race of your life, not many more chances to make it big. There are a handful of women such as yourself at the top of your sport. Competition is fierce.
Then you realise one of your opponents is Veronica Ivy, (previously known as Rachel McKinnon). 6 foot tall. She was Rhys McKinnon until the age of 29. Now 38, having lived most of her adult life as a man, benefiting from larger lung and muscle capacity, leg length and testosterone, albeit slightly reduced, she now dominates women's cycling at this high level. This is where the problem lies. In her professional work it doesn't matter one jot whether Veronica is male or female and her name and pronouns are up to her, but when someone such as Veronica then competes in sports against biological women, there is huge unfairness. Across the sporting arena there are others like her, dominating their sport pushing biological women out.
Veronica has a certificate to say that she is female and allowed to compete against women. Perhaps she does, but morally, is she right to grab the glory leaving biological women behind.