She first appeared in X-Men #4 where she and her twin brother Pietro a.k.a Quicksilver were supervillains and founders of the Brotherhood of Mutants. They were led by Magneto, whom they joined to escape persecution from non-mutants until they reformed and joined the Avengers.
The character's popularity only skyrocketed when she appeared in the MCU, played by Elizabeth Olsen. Despite Olsen's talent and remarkable portrayal of the character, it led to one question: Is Wanda whitewashed in Marvel?
Trigger Warning: This article contains some sensitive terms and some details of the Holocaust.
Is the scarlet-clad Wanda whitewashed or not?
Jewish and Romani heritage
Wanda has a complicated history in regards to her ethnicity and background owing to multiple retcons in Marvel. From being the Jewish Magneto and his Romani wife, Magda's daughter to being the daughter of Natalya Maximoff and at one point her brother Django and his wife Marya's adopted child, her half-Jewish, half-Romani history remains intact.
The Jewish and Romani people faced a lot of bigotry, racism and persecution, especially with the Holocaust. While she did not face this, it did impact her background and ethnic roots. Her, and by extension her twin brother's, depiction as heroes and noble warriors was something of a rarity in the general depiction of Romani people.
Her complexion in the comics also kept changing. Her olive/brownish skin eventually turned white thanks to artists whose renditions of her kept changing overtime due to artwork differences and color usage. The cover of Damage Control #1 (2015) showed her as white, even though she only has a minor role in the story. The writers, however, cannot be solely blamed as editorial intervention has caused problems as well.
White people with Jewish and Romani heritage were also not considered "proper white" despite their appearance technically being white.
Disney enters the fray
When Disney and the MCU entered the fray, that was when the argument regarding Wanda's whitewashing began. Disney's decision to cast a blonde actress with white skin as the character rather than someone of a Jewish or Romani heritage brought up comments from several fans who believed she was whitewashed. This also showed how the now-usually woke Disney ignored the Jewish-Romani minority.
The character was also depicted as Christian and eastern European, wearing a cross on her neck and also sporting a Russian-esque accent. Over time, this became American as part of her characterization. This "attempted whitewashing" once again invited comments.
The character, in her first appearance being depicted as a HYDRA agent (or voluntary experiment), also added to the whole whitewashing argument. HYDRA in the comics is a Neo-Nazi group, led by the Red Skull who is a literal Nazi.
If you know the Nazis (and Hitler), they only preferred blonde haired, blue-eyed, white people and persecuted and killed Jewish people via concentration camps and the Holocaust.
What did Disney do? They cast a blonde, non-Jewish and white actress to play the character. This spoke volumes and no doubt only served to only fuel the whitewashing claims and statements.
The fifth episode of WandaVision also angered several fans who saw Disney/Marvel imply a slur used for Romani people. This was when the character described her Halloween costume as a fortune teller, which is a stereotype people often associate with Romani people.
Elizabeth Olsen uses the slur word
In several interviews, most notably during her appearance on the Graham Norton show with Mark Ruffalo and Jeremy Renner, Elizabeth Olsen used the word, which angered a lot of people, but more anger was directed at Marvel for not cluing her in on her character's history.
Why, you may ask? It was because Romani people look at that word as both derogatory and offensive. Several people have stated that the use of that word doesn't just enforce racial stereotypes on Romani women, it also dehumanizes them.
There are also fans who believe that she was not whitewashed and that she is white in appearance and that only her ethnic origins are tied to the Romani people. Recent Marvel comics have also shown her as white, who as a child was experimented on by the High Evolutionary.
Ultimately, the question of the character's whitewashing cannot really be answered in a straightforward way as it is a complicated issue, owing to comic retcons, various artistic interpretations, polarizing opinions and so on.