Pinyin tone errors from ignored tone sandhi
The mistake
Most Anki HSK decks copy pinyin directly from online dictionaries. The problem is that dictionaries list the base (citation) tone of each character, not the tone the character actually takes in context. The most common case is third-tone sandhi (三声变调): when two third tones appear in sequence, the first one shifts to a second tone. 你好 is written nǐ hǎo in dictionaries, but a native speaker actually pronounces it ní hǎo. If your flashcard teaches you to read 你 as a third tone inside this word, you will sound foreign the moment you speak.
Tone sandhi does not stop there. 一 (yī) changes to a fourth tone before a first, second, or third tone, and to a second tone before a fourth tone. 不 (bù) flips to a second tone before a fourth tone.
What to do instead
A correct flashcard must store the contextual pinyin, not the dictionary pinyin. When you audit a deck, open any card containing two adjacent third tones and check whether the first tone was adjusted. In my experience, roughly eight out of ten community decks get this wrong.
Example
你好 — dictionary: nǐ hǎo → spoken: ní hǎo