Why is the background color of my MUI TextField changing after I enter data and how do I prevent that?

I have a TextField inside a FormControl inside a Styled Control (Paper) that looks like this:

const StyledPaper = styled(Paper)(({ theme }) => ({
  backgroundColor: "#99d6ff",
  width: '90%',
  justify: 'center',
  textAlign: 'center'
}));
...
<StyledPaper square={false} >
  <FormControl variant="filled" fullWidth>
    <TextField
      id="loginInput"
      label="Login"
      InputLabelProps={{ shrink: true }}
      value={login}
      onChange={() => handleInputChange("loginInput")} />
  </FormControl>
</StyledPaper>

The problem I’m having here is that when you select the TextField and fill it with an autocomplete, the background changes to white (the color of the autocomplete background). If I just type and don’t use the autocomplete the background remains as I intended from the StyledPaper. How can I prevent the background color change?