An angry red face with a black bar and white Grawlixes on its mouth indicates that it is swearing or being vulgar.
Grawlixes are printed symbols representing swear words or obscenities (e.g. @#$%&!) . It is usually used to express anger, frustration, or raging outbursts.
Most platforms feature the same eyes as on their ? Angry Face.
Face with Symbols on Mouth was approved as part of Unicode 10.0 in 2017 under the name “Serious Face with Symbols Covering Mouth” and added to Emoji 5.0 in 2017.
U+1F92C
? Serious face with symbols covering mouth