i don’t think i’ve ever experienced a block before but more so repeating the same vowel and consonant over again (so repetition, idk ab prolongations). for me, it really depends because one moment i’ll be able to start a sentence perfectly and the next it’s just me struggling to even pronounce the word. this is very common for w’s and p’s but again it depends because even i can’t list out all the different letters this has happened w lol.