On winning the gold medal in the women’s kata event at the Tokyo 2020 Olympics, Sandra Sánchez waved a blue-white-blue horizontal triband flag with a coat of arms in the center. The coat of arms includes a crown on top of what seems to be a fortified tower with a red background.
The full flag can be seen in this YouTube video from Eurosport (at 5:19). I am also posting a partial screenshot showing the colors and coat of arms here:
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