Transgender: The superset of all those persons who act out the other gender role in society. This includes transvestites and transsexuals. Andy Weir, 5 February 2001
The Transgender Flag (for those who act, dress, or otherwise identify as the opposite gender) appears to be a brand new invention. Steve Kramer, 29 November 2000
There's little agreement about a flag for the community, although a symbol of a pink triangle with a combined male and female symbol ("⚥") in the center has become the most common symbol by far. (I'd actually never seen the two flags you show. But then, the interesting part of all this is how such a community acquires a symbol.) Anne Ogborn, 12 December 2005
The most widely known transgender flag. It's a pale pink, white and baby blue set of horizontal stripes. Vanessa Foster, 17 February 2003
Monica Helms, who is a TG activist now living in Arizona, designed the transgender flag several years ago. She has told me that the original is now in a transgender or rainbow museum, but I know not where. Willow Arune, 16 February 2003
Wondering where it might be, I saw another article that it might be at the U.S. "National Museum of American History" (in Washington, DC). This was confirmed by an agent there: Matt MacArthur, in the below email. Apparently, this flag is object/item#1694617.
I wouldn't go as far as to consider it a new variant, since the sexual orientation flags usually don't have the prescribed color shades, and in this case, it may be just the lighting conditions during the making of the photo which make the pink look different. Tomislav Todorović, 7 July 2016
"Helms devised the transgender flag in 1999, 20 years after the introduction of the rainbow flag for the LGBT community. Just like the American flag represents the whole country but each state has its own flag as well, Helms feels like “the rainbow flag is the LGBTQ flag for everybody, and each individual group can have their own flag for their own individuality."
In fact, she was inspired to create a flag for the trans community by Michael Page, who had designed a flag for the bisexual community the year before. Following his example, Helms says that “it was almost like waking up from a dream and seeing it.” She drew it out, contacted the same company who had created Page’s bi pride flag, picked out some swatches, and about a week later she had the first flag. It was that very first flag that she donated this month.
The trans flag has five stripes. The outer two are light blue and the inner two are light pink, representing the traditional colors for baby boys and baby girls, while the middle stripe is white to represent “those who are intersex, transitioning, or consider themselves having a neutral or undefined gender.” Helms designed it to be horizontally symmetrical so that “no matter which way you fly it, it is always correct, signifying us finding correctness in our lives.” Helms’ design was further adapted in a flag designed in 2010 by Marilyn Roxie for the genderqueer and non-binary communities.
In regards to how the trans pride flag caught on with the community, Helms explains, “I just used it everywhere and anywhere,” beginning with the 2000 Phoenix Pride parade and then at marches, conferences, Transgender Day of Remembrance ceremonies, and other events since then. “People caught on and decided that they wanted one.” She has since seen it displayed in various countries across the world, noting that she recently saw a picture of it displayed in Peru." David Phillips, 27 July 2017 Source: https://thinkprogress.org/transgender-pride-flag-designer-applauds-smithsonian-lgbt-artifacts-collection-51a7d1ade112
A variant of this flag adds a large transgender symbol in white, fimbriated black, upon the field. The symbol was created in 1993 by transgender activist Holly Boswell  and represents a combination of astronomical/astrological symbols for Mars and Venus, which stand for male and female genders, respectively, with addition of a third "branch," an arrow crossed by an additional stroke, for "mixed" gender identities. The symbol has been included into Unicode since version 4.1.0 and assigned the code point U+26A7.
Queer Nation's transgender focus group, Transgender Nation, created T-shirts and banners based on the pink triangle on white design. Dawn Holland added a symbol in the center with 4 circles interlocked, with the cross sticking up and right, the arrow down, the cross down on the left, and the arrow up to left, symbolizing various transgendered people working together.
For what it's worth, it happened in about Oct 1991 in a sandwich shop (San Francisco, Calif., US) on Castro between 17th and 18th. The original T-shirts were printed with a home silk screen kit on the floor of my apartment, and the original banner was created in my back yard. The banner and an original T shirt are in my possession at moment, but are on permanent loan to the G&LHS in San Francisco. Anne Ogborn, 12 December 2005
I have created a design for a Transgender flag info on the flag and graphics for it can be found at my website. Jennifer Pellinen, 20 July 2002
It surely is similar to the bi-sexual pride flag, and certainly bears the same symbology: a transition range from blue (male) to pink (female) — and/or inversely. The number of stripes may convey a symbolic reference to what makes the difference between a bi-sexual and a transgender, or perhaps is just an unrelated reference to the gay pride rainbow flag.
(A challenge for vexillonomists: how would you describe this flag, especially the color names?
Proposal: P− Pb− Pb Pb+ B — now the words: pink, fuchsia, lilac, plum, blue? A comment: It would look much better with a much darker blue.) António Martins, 22 July 2002
image by Tomislav Todorović, 21 May 2020, based on original image by António Martins, 1 April 2005