can't hear you
A linguistics and education professor from Michigan State University claims that telling somebody that you can't understand him is an example of "linguistic racism."

More specifically, it's "racist" to ask a person to repeat what he said because you "don't understand [his] thick accent" (does anyone actually say that ... especially the "thick" part?).

Another example is someone "openly say[ing] only English is to be spoken in the workplace" despite the presence of multilingual employees.

So says Professor Peter De Costa, who in an interview with MSU Today defines "linguistic racism" as "acts of racism [...] perpetuated against individuals on the basis of their language use."

De Costa places some of the blame for current linguistic racism on the outgoing presidential administration due to its "jingoistic sentiments that target speakers who do not use the dominant language." Those who don't (or can't) speak English, the prof says, are "perceived as being unpatriotic and unwilling to embrace American values."

There's also the president's "false labeling" of COVID-19 as the "Wuhan Virus" which "fueled xenophobic resentment" against Chinese and Chinese-Americans. Such gave the virus an "ethnolinguistic quality," De Costa says, which subjected that demographic to "blatant dehumanization" and "unnecessary ostracization."

From the story:
On a less visible level, the affective dimensions of linguistic racism can stir negative emotions, such as shame and guilt. Minoritized speakers might become ashamed of speaking their home language, which over the course of several generations could result in language loss. ...

A good starting point [in recognizing whether or not folks are committing acts of linguistic racism] would be to acknowledge the existence of a race-biased monolingual standard ideology that favors white, affluent mainstream speakers. We need to recognize that multilingualism and multidialectism are social realities, and that it is not uncommon for multilingual speakers to shuttle back and forth between different languages and language varieties when they communicate with other multilingual speakers. Such a linguistic practice should not be seen in critical, deficit terms; rather, such verbal shuttling is a linguistic and cultural asset, and not something to be remediated.
Is it actually "racist" to ask English to be spoken at work, or to suggest to those with heavy accents to work on accent reduction? Or are these legitimate and sensible suggestions for English-learners to succeed in an English-dominated society?

De Costa elaborates further in his article "Linguistic racism: its negative effects and why we need to contest it" published in the International Journal of Bilingual Education and Bilingualism.