Google Search Console Error (5xx)

Hello,

I have problems with my WordPress page and the Google Search Console.

I have 59 pages that have a server error (5xx)

The faulty pages look like this:

https://www.nain-schiffsmodelle.com/4/historische-segelschiffe-c-22_23.html?currency=NOK

https://www.nain-schiffsmodelle.com/riva-aquarama-replica-blauwei-p-224.html?currency=GBP

https://www.nain-schiffsmodelle.com/riva-aquarama-replica-blauwei-p-224.html?currency=RUB

If you delete the part after the .html, the pages will be accessible again.

How can I remove the currency from the URL or set it so that Google doesn’t see this as an error anymore?

Thanks in advance.

The page I need help with: [log in to see the link]