I’m not sure how simply adding the word LGBTQ to a prayer service furthers an agenda.
Catholic churches have indeed in the past had services or Masses for specific groups. For example, Mass in Polish, or prayer service for first responders, or Red Mass for lawyers, or prayer service for persons struggling with addictions or homelessness. All of these things are generally open to whoever wants to show up, but it’s understood there will be Polish people, or lawyers, or recovering addicts, etc there.
How is an LGBTQ Vespers any different? If you get there and there’s a deacon giving a talk before the prayers on how we should all support gay marriage, then I can see the discomfort. If it is simply a prayer group open to all but with a focus on one group that needs to pray and receive prayers right now, how is this any different from a service for homeless people?