There's a little bit more to it. The main organiser, who was an actual events manager, quit a few months ago and the org went to a volunteer-led model. Andi Herring basically founded and ran the thing previously. Then those vols voted to end their sponsorship with Barclays a few weeks ago, which has been a LONG running argument. ...I tried to link to an open letter but MN is blocking me - google it.
The cancellation notice on FB said it was about trans, and it likely was, but it's also been a long running debate for years. A lot of people are against corporate Pride, for all kinds of different reasons.
Anyway now they've no money and no skills, so it was inevitable, really. It's a really massive job, organising a city centre street parade and free festival, especially given the recent goings on.
So far as I know, there's not any gay or lesbian people actually running the thing any more. It's trans, bi+ and allies. (Willing to be wrong there - I haven't researched this, just gossip!)