Hello!
Why does my account have: Bidding restrictions on your account? At the moment, I have a German ebay account of my relative in Germany, but for some reason the sniper does not work. What could be the reason?

I have no way to check without the item number.
Anyway, if you don't want to share it, that's not your account. This is an item-specific restriction set by the seller.
Your manual bid would not work too due to the same restriction.