The transgender identity is relevant here, but its only one part of the picture.
This has all the hallmarks of 764/O9A.
O9A (Order of the Nine Angles) is a satanic organisation established in the 1970s in England which later went international, linking up with global neo-nazis, particularly in the US, Russia and Ukraine. From the beginning it was associated with child and animal sexual abuse.
764 is a relatively new development associated with O9A, where O9A members recruit children and youth through Discord, Roblox and Telegram, they particularly target children/youth who have mental health issues (esp anorexia); are gender confused or self harming. They circulate gore and illegal porn and demand gore (often of killing animals) or extreme porn, and use threats to them and their family members to obtain it. The ideology is nihilist/accelerationist/pro-mortalist, and sometime referred to as "soup" as it has no clear political base except violence. It recruits heavily from trans youth because of the centrality of death in trans ideological tropes (dead name, trans day of remembrance, lack of reproductive ability, extreme body modification despite risks to life/health, dead son/trans daughter, trans genocide etc etc etc)
This shooter and several others in the US, fit a clear profile of 764 grooming. (heavy online presence, trans/gender-confused, use of Cyrillic alphabet, known O9A symbols used, ideological soup).
I'm in no way suggesting that this excuses his actions, what I am pointing out is that there is a far bigger threat here. This violence isnt individual and random, its co-ordinated and encouraged online. 764 is known to be active in the UK. Two young men have already been arrested in connection with it, and there are a couple of incidents in the UK (incl. Southport and Edinburgh) where I think it is at least possible that there may be a 764 connection. Associated organisations include "CVLT", "com", "Manic Murder Cult", "Terrorgram" and "Harm Nation".