PictureUrl in User Profile cannot be displayed - LineBot Message API

Hi Line team,

Recently, I've developed a linebot which will store members in group's pictureUrl, and display the image in flex message. I collected the picturel url from bot received message event -> source -> profile -> pictureUrl. Mostly, the picture can be displayed properly. But some member's image just cannot be displayed, these image cannot even be opened while I paste the pictureUrl to browser.

I've check the pictureUrl, and found there are sightly different.

Normal pictureUrl: https://profile.line-scdn.net/<long string with number and letter> Abnormal pictureUrl: https://profile.line-scdn.net/<shourt string with number only>

Looking forward for your respond. Thank you.