It says that the number is incorrect and does not allow me to place a bid. The same thing happens with other eBay auctions. What is going on here? Is there some kind of malfunction?

Hello Gediminas,

Thanks for the report. This is working now. eBay had hard-expired our app token without telling us.

I hope this has been explained to your satisfaction. Thank you for writing in, and please let me know if you have any other questions.