Mandarin dialect pronouncing sizzling consonants differently
MDBG


  翹舌音
  
  翘舌音[翹舌音]
  
  qiào​shé​yīn​
  
  retroflex sound (e.g. in Mandarin zh, ch, sh, r)


It could be accent, it could be dialect it could be 大舌头 (a big tongue).


翘舌音 is almost nonexistent in Taiwan, although it should be, so I'd say that's down to accent.
Many topolects, like Sichuanese, don't carry retroflex sounds, and that's dialectical.
Some people do have speech impediments or just a big tongue, as some like to put it.


You can call it lack of retroflex or 没有翘舌音.



The guy in the scene from Silicon Valley seems to be channeling a Taiwanese accent.