Why is my Vauxhall Insignia's brake pedal spongy?

I recently purchased a used Vauxhall Insignia and I noticed that the brake pedal feels spongy when I press it. It doesn't feel as firm as my previous car. What could be causing this issue and how can I fix it?

Most likely, there is air trapped in your brake lines which is causing the spongy feeling. You may need to bleed your brake system to remove the air.

Another possible cause could be worn out brake pads. Check the condition of your brake pads and replace them if necessary.

It could also be an issue with your brake hoses or master cylinder. I recommend bringing it to a certified mechanic to diagnose and fix the issue.