My application is using the following request’s handling chain:

Nginx Server -> Nest.js HTTP controller -> Nest.js service and PostgreSQL connection.

It supports sending parameters for filtering results in the following way: the filter parameter is sent, which is an array of objects:
hostname.com/posts?filter=[{"property":"title","operator":"=","value":"RAW234"}]

This construction with operator property is further transformed into the SQL query like:
WHERE title is 'RAW234' . I would like to allow users to send ‘ILIKE’ operator to filter result with wildcard. My filter parameter will be: filter=[{"property":"title","operator":"ilike","value":"%234"}] and here I got a problem – my app is not able to parse filter query parameter with JSON.parse() method further in the request processing chain.

I find that my Nginx server receives all queries as:
GET hostname.com/posts?filter=[{%22property%22:%22title%22,%22operator%22:%22ilike%22,%22value%22:%22RAW234%22}] – this is an expected behavior – the browser encodes special characters in the request.
Next, the filter parameter comes to the Nest HTTP controller in the proper form: '[{"property":"title","operator":"ilike","value":"RAW234"}]' and I can parse it with JSON.parse() without any issues.
But if I use % symbol in the value property as: [{"property":"title","operator":"=","value":"RAW%"}], my Nest HTTP controller receives it as [{%22property%22:%22title%22,%22operator%22:%22=%22,%22value%22:%22RAW%%22}] – " symbols encoded to %22 – this is not a valid JSON and JSON.parse() returns an error.
Only this special character % breaks this handling chain – with any other ^ & ($#@ it work without problems.
My Nginx config for this route looks like:

 location ~ ^/posts/?(.*) {
      proxy_set_header   Host             $host:$server_port;
      proxy_set_header   X-Real-IP        $remote_addr;
      proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
      proxy_pass http://$post_microservice_backend/posts/$1$is_args$args;
    }

Nginx forwards external requests to HTTP-controller in post_microservice_backend HTTP-server which is powered by Nest.js.

1. Is it possible to receive filter parameter as [{"property":"title","operator":"ilike","value":"RAW%"}] when I use % symbol?
2. Maybe it is my Nginx settings issue?
3. I tried to use decodeURIComponent but it can not parse invalid string. Of course, I can use regular expressions and similar methods to transform a string to get a valid value, but maybe I can change some setting so that it works right away?