The places where we are not getting the description is because of these meta Tags:-

// https://www.ecoleglobale.com/blog/

<meta name="robots" content="follow, index, max-snippet:-1, max-video-preview:-1, max-image-preview:large">

here the max-snippet is given value -1 and in this case Google will choose the snippet length that it believes is most effective (to help users discover your content and direct users to your site.)

//https://www.ecoleglobale.com/blog/ecole-globale-2/

<meta name="robots" content="follow, index, max-snippet:15, max-video-preview:15, max-image-preview:large">

in this case max-snippet:15 so its showing only 14 characters excluding spaces.

These are the bugs which I have found out.