I was looking at the FOAT chart and noticed the price difference between diff contract months can be ridiculously wide.

For example, look at the gap between the most recent contract month and the previous one for FOAT:

https://www.sierrachart.com/image.php?Image=1558816655712.png

I see similar gaps on the FBTP (italian bonds) charts.

Can someone explain to me why the gaps are so huge with these European bond instruments?

I don't know the instrument you have posted, but if you are interested in trading European Bonds, you have to watch the German Bund (FGBL), this is one of the most liquid and most traded instrument worldwide.