It is definitely transphobic to deliberately misgender a transgender person: e.g., to refer to a transgender woman as a “man” or “male” (except in a technical discussion where for some reason it’s relevant to mention the fact that she has biologically male genes or birth anatomy).
I don’t think I’ve been accused of that, but I do try not to misgender people.
As discussed in the other thread you referenced in your OP, there are some verbal ambiguities where, for example, we all recognize that a term like “pregnant women” is a reasonable approximation to the more accurate expression “pregnant people, including for example pregnant cisgender women, who make up the vast majority of pregnant people, and pregnant transgender men”.
I don’t think people generally get called transphobic for using those reasonable approximations. If somebody does get all accusatory about such an approximate term being used in good faith and with no intention of offense, I think the accuser needs to dial it back and give the accused a break.
Now, what does tend to get people called transphobic, and not without reason IMHO, is when they make a big fuss about supposedly not being “allowed” to use those reasonable-approximation terms anymore.
Or when they whine about other people choosing to use more general and inclusive terms, such as “pregnant people” rather than “pregnant women”.
Or when they make a big fuss about the semantic decoupling between terms denoting gender (such as “woman”) and terms denoting biological sex (such as “anatomically female” or “having a naturally occurring vagina”).
If you’re willing to take all those emergent linguistic phenomena in your stride and accept that they’re just part of the way that language is changing as we develop more insight into the complexities of sex and gender, then I don’t think you’re doing anything that could reasonably be called “transphobic”.
But to be fair, it is not always easy for me to figure out exactly what you are saying in your posts. Case in point:
Sorry, but could you please explain in more detail what you mean by these two sentences? Both of them were apparently posted in reply to me, but I really am not following your train of thought in either of them.