What it means: 'Trans Agenda' is the attempt to suggest that transitioning (especially medically transitioning), trans awareness and trans equality are all being pushed by ominous figures in the 'Establishment'. The 'Establishment' here includes 'big pharma (major multinational pharmaceutical companies collectively as a sector of industry.)' and 'globalists' (a rightist term describe 'unpatriotic' capitalists), e.g George Soros (a Jewish Billionaire who often supports progressive leaning projects around the world), and often ties in with antisemitic tropes of Jewish plots to undermine white patriarchy.
I would just say that it's obvious there is a "trans agenda", but you don't need to appeal to anything like "Jewish plots".
Rather, just look at the openly published material from left-wing political groups and "human rights" organisations or whatever.
I mean, the Green Party is pushing the trans agenda themselves!