看起来路由工作正常。
查看此演示：

package main

import (
    "fmt"
    "net/http"

    "github.com/go-chi/chi/v5"
    "github.com/go-chi/chi/v5/middleware"
)

func main() {
    r := chi.NewRouter()
    r.Use(middleware.Logger)
    r.Use(middleware.Recoverer)

    r.Get("/v1/companies/{companyId}", func(w http.ResponseWriter, r *http.Request) {
        companyID := chi.URLParam(r, "companyId")
        fmt.Println("companyId:", companyID)
        _, _ = w.Write([]byte(companyID))
    })

    http.ListenAndServe(":8080", r)
}

使用cURL发送请求：

$ curl -i 'http://localhost:8080/v1/companies/CN%3DCS.Test%20Company%20Hello%2COU%3DWorld%2CO%3DHello%2CdnQualifier%3Dm1Ws%5C%2BnFSkqy1xBrYUTbxGpzLEcg%3D' 
HTTP/1.1 200 OK
Date: Thu, 24 Aug 2023 03:44:33 GMT
Content-Length: 107
Content-Type: text/plain; charset=utf-8

CN%3DCS.Test%20Company%20Hello%2COU%3DWorld%2CO%3DHello%2CdnQualifier%3Dm1Ws%5C%2BnFSkqy1xBrYUTbxGpzLEcg%3D

顺便说一句，请注意，该值是在路径中使用的，而不是在查询中使用的。如果你在JavaScript中编码这个值，你应该使用encodeURI而不是encodeURIComponent。下面的代码片段显示了差异：

console.log(encodeURI('CN=CS.Test Company Hello,OU=World,O=Hello,dnQualifier=m1Ws\\+nFSkqy1xBrYUTbxGpzLEcg='));
// CN=CS.Test%20Company%20Hello,OU=World,O=Hello,dnQualifier=m1Ws%5C+nFSkqy1xBrYUTbxGpzLEcg=

console.log(encodeURIComponent('CN=CS.Test Company Hello,OU=World,O=Hello,dnQualifier=m1Ws\\+nFSkqy1xBrYUTbxGpzLEcg='));
// CN%3DCS.Test%20Company%20Hello%2COU%3DWorld%2CO%3DHello%2CdnQualifier%3Dm1Ws%5C%2BnFSkqy1xBrYUTbx

然后使用从encodeURI返回的值：

$ curl -i 'http://localhost:8080/v1/companies/CN=CS.Test%20Company%20Hello,OU=World,O=Hello,dnQualifier=m1Ws%5C+nFSkqy1xBrYUTbxGpzLEcg='
HTTP/1.1 200 OK
Date: Thu, 24 Aug 2023 03:54:59 GMT
Content-Length: 83
Content-Type: text/plain; charset=utf-8

CN=CS.Test Company Hello,OU=World,O=Hello,dnQualifier=m1Ws\+nFSkqy1xBrYUTbxGpzLEcg=