this is quick tutortial that works with EG and someone can try and see if it works for or something similar for microsoft version.

1. go to your rules folder and create a file called namerchanger.json
and add this to it: [{"accountId":"paste account id here","displayName":"your spoofed name","preferredLanguage":"ru","linkedAccounts":[]}]

2. open up your game and have fiddler running and captrue https requests. once in the lobby, go to fiddler and search AccountID and find the accountid from any highlighted ones and copy and paste your acount id and paste it to the json file you created earlier.

3.exit the game, go back to fiddler and add new rule and have this as the URL header:
EXACT:h t t p s://api.epicgames.dev/epic/id/v2/sdk/accounts?accountId=PASTE YOUR ACCOUNT ID HERE
and add the namechanger.json file to it.

4. dont forget to add your account id to both the json file and also at the end of the URL header, and obvisouly get rid of the space in the https. in the displayname section put whatever name you want in it.

5. save the rule you created on fiddler and launch the game back up and your name should be changed/spoofed to you and also others.