Dyslexia was a type of learning disability.
A time-traveling Gabrielle Burnham observed that Spock's dyslexia allowed him to process the effects of atemporal dysplasia. Together with his logic training and Human emotions, this helped him comprehend her existence. (DIS: "Perpetual Infinity")
The script for Star Trek IV: The Voyage Home had Gillian Taylor asking James T. Kirk whether he was "dyslexic on top of everything else" after he said "LDS" instead of "LSD". The scene remained in the final version of the movie, but without mention of dyslexia.
Part of a scene in DS9: "Image in the Sand", involving Julian Bashir, Miles O'Brien, and Quark, was used in a 2001 Dutch PSA to raise awareness for dyslexia by SIRE. The footage is overlayed with increasingly garbled subtitles (basically correct translations, but spelled wrong) It then cuts to a spoof of the DS9 intro, with messages like "trouble reading?" and "People with dyslexia have trouble on a daily basis" styled like the actors credits.