The claim that sharpie pens aren't readable by voting machines is baseless and false. Sharpie pens is a preferred pen for filling out ballots.
A Sharpie is a common brand of marker pen manufactured by a U.S. based company, they are typically felt tipped with quick drying ink.
During the 2020 US election, a social media post claimed that a voter witnessed inside her polling place election workers forcing some voters to use Sharpie permanent markers to mark their ballots and that the voting machines were not reading those ballots. The video led many to suggest that this was an effort to block the votes of people supporting President Donald Trump.
However, that claim is false and misleading. A video released by the Maricopa County Elections Department on YouTube states that one can use a black or blue pen or Sharpie to fill out your ballot in Maricopa County. It further states that voting centers are using fine-tip Sharpies because it is the fastest-drying ink and works best on the tabulation equipment. Therefore, the Sharpie is a preferred pen for filling out ballots in Maricopa County, and voting machines ballots filled out using Sharpies.