My comment is based on some articles from years ago about Germany and maybe other countries having trouble getting their gold back from the US. Googling a bit now results in a couple of articles that say that Germany did eventually get their gold back, but there were some hiccups and delays that made people wonder whether the gold was even there at all.

https://bmg-group.com/germanys-gold-reserves-u-s-paper-claim...

https://www.rt.com/business/445133-germany-access-gold-us-fe...

https://www.kitco.com/news/2017-08-24/Germany-Gets-Its-Gold-...

Turns out everything is fine, but a couple of years ago, people were worried about this. It looks like only Germany was involved and no other countries.