Steps to reproduce:

1. Open the trigger "Nginx: Failed to fetch stub status page" in "Nginx by HTTP" template
2. Try to update find() function in trigger expression from:

   find(/Nginx by HTTP/nginx.get_stub_status,,"like","HTTP/1.1 200")=0
   

   to:

   find(/Nginx by HTTP/nginx.get_stub_status,,"regexp","HTTP\/[\d.]+\s+200")=0
   

Result:
Cannot update trigger. Invalid parameter "/1/expression"...

Expected:
Expression must be applied correctly. Zabbix 6.0 is not affected and expression works in 6.0.18. Upcoming 7.0 might be affected as well as 6.4.