During the 1960s and 1970s when more and more evidence was showing the real harm caused by smoking the tobacco companies created a tactic to fight back - Manufacturing uncertainty.
Here's what a tobacco executive said: “Doubt is our product since it is the best means of competing with the ‘body of fact’ that exists in the minds of the general public. It is also the means of establishing a controversy.”
This tactic is also used by racist anti-Semites when denying the Holocaust. There are a few people who know a lot about the Holocaust, there's the bulk of the population who know a bit (and it's fair to say some people don't know much at all) but who are not denying the Holocaust, and there's a group of racists who seek to deny the Holocaust. The tactics used by those Holocaust deniers follows a similar pattern to big tobacco: they ask questions that aren't easy for the general public to answer, that create uncertainty about the Holocaust. These have all be fully answered by historians, and there's a useful guide from the Debunking Denial.
We can see similar tactics being used by a small group of vocal anti-Trans activists. One of the questions they've seeded, that gets repeated by people who are not themselves anti-Trans, is "We don't know about the long term effects of these meds". And to most people this sounds reasonable -- we don't know about the long term effects, and maybe that's worrying. But here's the thing: those anti-trans activists do not care about the long term effects. It doesn't matter if there are long-term effects or not. They're only sowing confusion. Those activists only care about meds used by trans-people. They never mention the serious concerns we have about long term effects of a wide range of other medication. And scientists and doctors being honest (we don't think there's anything to worry about, we can't see a plausible mechanism of harm, but we don't yet have data) have that honesty twisted by campaigners.
We do not let conversations about the Holocaust be driven by anti-Semites. We shouldn't let conversations about gender identity treatment be driven by a small vocal group of activists.
So, when I say there are parallels here to anti-Semitism I do not mean that people asking these questions are equivalent to anti-Semites, or are themselves anti-Trans activists. (But I accept that I need to do a better job of communicating.)