Upload of file with plus  character in name (example is 1+.docx), will result in the following error on access:
"Can not find data record in database table resource."

In looking at some other special characters, some are encoded and some are stripped. Plus correctly appears as %2B in the URL generated for access.

This task has already been, but for earlier versions of the moodle (https://tracker.moodle.org/browse/MDL-23567). There was also no solution.

I'm facing the same problem Now 

Moodle 4.0.2, IIS 10, PHP 8.0, MariaDB 10.8

<requestFiltering allowDoubleEscaping="true"/>