我想出了解决办法
解决方法：
我修改了自定义控制器中klubr内容类型的findOne方法。关键是创建一个递归函数getFullPopulateObject，该函数为Strapi的查询系统构造一个完整的填充对象。该函数考虑不同的字段类型，如组件，动态区域，关系和媒体。

"use strict";

     const { createCoreController } = require("@strapi/strapi").factories;

module.exports = createCoreController("api::klubr.klubr", ({ strapi }) => ({
  async findOne(ctx) {
    const { id } = ctx.params;
    const entity = await strapi.db.query("api::klubr.klubr").findOne({
      where: { slug: id },
      ...getFullPopulateObject("api::klubr.klubr"),
    });
    const sanitizedEntity = await this.sanitizeOutput(entity, ctx);
    return this.transformResponse(sanitizedEntity);
  },
}));

const { isEmpty, merge } = require("lodash/fp");

const getModelPopulationAttributes = (model) => {
  if (model.uid === "plugin::upload.file") {
    const { related, ...attributes } = model.attributes;
    return attributes;
  }

  return model.attributes;
};

const getFullPopulateObject = (modelUid, maxDepth = 20, parentModelUid = null) => {
  if (maxDepth <= 1) {
    return true;
  }
  if (modelUid === "admin::user") {
    return undefined;
  }

  const populate = {};
  const model = strapi.getModel(modelUid);
  for (const [key, value] of Object.entries(
    getModelPopulationAttributes(model)
  )) {
    if (value) {
      if (value.type === "relation" && value.target === parentModelUid) {
        continue; 
      }
      if (value.type === "component") {
        populate[key] = getFullPopulateObject(value.component, maxDepth - 1);
      } else if (value.type === "dynamiczone") {
        const dynamicPopulate = value.components.reduce((prev, cur) => {
          const curPopulate = getFullPopulateObject(cur, maxDepth - 1);
          return curPopulate === true ? prev : merge(prev, curPopulate);
        }, {});
        populate[key] = isEmpty(dynamicPopulate) ? true : dynamicPopulate;
      } else if (value.type === "relation") {
        const relationPopulate = getFullPopulateObject(
          value.target,
          maxDepth - 1,
          modelUid // Pass the current model as parent
        );
        if (relationPopulate) {
          populate[key] = relationPopulate;
        }
      
        
      } else if (value.type === "media") {
        populate[key] = true;
      }
    }
  }
  return isEmpty(populate) ? true : { populate };
};

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这种方法成功地填充了findOne查询中的所有相关字段。我希望这个解决方案可以帮助其他使用Strapi中自定义控制器的人。