I see, so you don’t have the actual files in n8n but instead have URLs you want to share in Telegram? And these URLs would come through as an array in a single attachments field for each of your items?
My suggestion would be an approach like this: Convert each individual string in your attachments arrays into individual items. Afterwards you have exactly one photo per item and can set up the Telegram node to handle only one attachment. Here is an example built on top of the workflow you have shared: