Material UI server side rendering

After a quick search in the codebase, I see two usages of the Hidden component:

  • The main one: to only render on client side
    <Hidden xsUp={!visible}>
      <TextField
        required={showAsRequired(required,
          appliedUiSchemaOptions.hideRequiredAsterisk)}
        id={id + '-input'}
        label={label}
        type={fieldType}
        error={!isValid}
        disabled={!enabled}
        fullWidth={!appliedUiSchemaOptions.trim}
        onFocus={onFocus}
        onBlur={onBlur}
        helperText={!isValid ? errors : showDescription ? description : null}
        InputLabelProps={{ shrink: true }}
        value={inputValue}
        onChange={onChange}
      />
    </Hidden>
  • Another one: to hidde the fieldset FormControl on big screen
    <Hidden xlUp={!visible}>
      <FormControl component='fieldset'>
        <FormGroup row>
          {options.map((option: any, index: number) => {
            const optionPath = Paths.compose(path, `${index}`);
            const checkboxValue = data?.includes(option.value)
              ? option.value
              : undefined;
            return (
              <FormControlLabel
                id={option.value}
                key={option.value}
                control={
                  <MuiCheckbox
                    key={'checkbox-' + option.value}
                    isValid={isEmpty(errors)}
                    path={optionPath}
                    handleChange={(_childPath, newValue) =>
                      newValue
                        ? addItem(path, option.value)
                        : removeItem(path, option.value)
                    }
                    data={checkboxValue}
                    errors={errors}
                    schema={schema}
                    visible={visible}
                    {...otherProps}
                  />
                }
                label={option.label}
              />
            );
          })}
        </FormGroup>
        <FormHelperText error>
          {errors}
        </FormHelperText>
      </FormControl>
    </Hidden>

In the first case of Hidden I’m not sure it’s really usefull to preserve the actual behavior: MUI support perfectly SSR. And the actual beavior could easily reproduced by the end user.

For the second case Hidden, I really did not understand why the field should be hidden on XL screen an up… Maybe you have an explanation? Or is it a typo ?