REST Webservice activity a slash "/" will be added at the end of the URL

An old problem:
Reference:  Client-sided updates: Workflow Designer 2021-12-08 366100  (version 7.5)

Problem:
When using GlobalVariables or IndexFields in a REST Webservice activity a slash "/" will be added at the end of the URL when executed by the Background Processing Service.

And now I had that problem in 7.11.  

Please help