I’ve noticed a similar tendency online to write “prejudice” or “bias” for “prejudiced” and “biased” (and so on), where you have a voiceless alveolar plosive following a voiceless alveolar fricative. In normal speech, of course, the plosive tends to be unreleased (or “unrelease”).

I think the most interesting thing about both cases is that writers are basing their spelling more on phonetic than on morphosyntactic patterns. There’s a generalisation they’ve missed. Other examples include “I would of” and punctuation used with regard to pauses in speech, but with no regard to syntactic structure.