Inline attachments' name in Email body html not visible

Question

When I copy and paste an image in email body and fetch the email body using Graph API, earlier it used to show the img tag in the email body html as <img size="8682" src="cid:image.png" style="max-width: 665px">, but now from past few weeks it shows some random guid instead of name in the cid.

Are there any changes that have been made in the email body html because it has broken my application's functioning?