Flag of Candar according to the Catalan Atlas of 1375. Flag of Eretnids Emirate (Principality) (Source: The Image of the World on Old Portolans. The Black Sea Littoral from the End of the 13th — the 17th Centuries (in Russian) by Igor K. Fomenko).
WARNING: This image is highly speculative. The main source pointing to this design is the Catalan Atlas, (File:Abraham and Jehuda Cresques Catalan Atlas. Eastern Europe view from the south.C.jpg) which as a historical primary source cannot be considered a reliable reference, especially if it is the only source used. This image should not be added to articles without clearly indicating its speculative nature.  Note that FOTW (where most of those flags on Commons are adapted from) is based on user contributions like Wikipedia, and hence not authoritative either.
Self-made in Inkscape, based on GFDL Image:Candar.png by en:User:Ingoman (James Dahl), https://search.rsl.ru/ru/record/01005530693
Superm401