Yes, the waiting lists are very, very long. I used to work in a job adjacent to dealing with complaints about the NHS, some about delays in referrals to gender services, and the outcome of complaints was generally, "it's not great but the NHS can't refer you to specialists that don't exist".
TRAs will have you believe it's transphobia or under-funding, but you can't magic specialist doctors who want to do this sort of work out of thin air. There just aren't that many of them. It's a niche area, as it should be, and the fact services are cluttered up with confused teenagers who have had their social contagion mindlessly affirmed by useful idiots isn't the fault of the NHS.
The fact that any autistic children (or those with other co-morbidities with gender/identity questioning) have been funnelled away from proper diagnosed and treatment and into services that affirm the idea they're the opposite sex should be a medical scandal.
