Based on the information you provided, there could be one of two possible situations.
- Freezer burn – check the product’s best by date on the package. If the date has passed, time and temperature fluctuations may have taken a toll on the vegetables, i.e. degradation or freezer burn, resulting in excess air in the package.
- Quality – If you have purchased the product in the past and the quality is off, I recommend you follow-up with the store where you purchased it or contact the food manufacturer.