I'm pretty sure Garnacho will be sanctioned, with a similar punishment to Bernardo. Bernardo's incident happened on 22 September 2019, the result of the investigation was announced on 13 November, and Bernardo was suspended from the Chelsea game on 23 November - two months after the incident. We shouldn't expect the FA to say anything about their process just yet, but they aren't ignoring it.
One difference between the two incidents is apparent though. The day after the Bernardo tweet, Kick it Out issued a statement saying, "We are extremely disappointed to see the tweet posted by Bernardo Silva, which has since been deleted.
Racist stereotypes are never acceptable as 'banter', and we're shocked that someone who is a role model to millions has failed to understand the discriminatory nature of his post.
The FA have been notified and we believe that retrospective action should be taken, including mandatory education - which is vital to challenge offensive behaviour such as this".
Bernardo currently has 4.5 million Instagram followers. Garnacho has 7.6 million Instagram followers, so his tweet has much further reach. It is rather telling that the body whose purpose it is to speak out against discrimination is itself showing discrimination, by not issuing a similar condemnation of the United player.