Thumbnail not displayed correctly in embed messages on certain servers

[ElieTaillard]

When sending an embed message with a thumbnail, the thumbnail is not displayed correctly on certain servers. The message is successfully sent to all servers, but the thumbnail is not visible on most of them.
I've checked that the bot has the necessary permissions and no exception is thrown.

Server 1:

Server 2:

As you can see, I use channel.send in a for loop, using the same parameters for each iteration. Why do I get a different result from one server to another?
https://github.com/ElieTaillard/PSTHC-DiscordBot/blob/1b42b66c5add9694bd91038b3579355e66e922e4/psthc_bot.py#L201-L221

[LostLuma]

This happens because you can not re-use a discord.File in multiple Messagable.send calls, as is stated in the documentation (read the Note!). What you will want to do is construct a new File using the same underlying file (the BytesIO instance, in your case) whenever sending it.

[ElieTaillard]

Ok thanks for that clarification. I'll fix my code and let you know if the problem is solved