Huge memory leak after mirror

I setup the gitea on my local server using rootless docker.
Since I just start to write my repo, there are only few (~10) repositories which mirror from github.
Just after restart the gitea docker, it only uses 100MB RAM, but in a day so it mirrors repositories, the RAM usage do not reduce back to idle.
It still remains about GB level.
Because of my deploy limit in docker configuration, it does not use whole of memory, but it is weird where it constantly use RAM.

Is there any configuration issue about it? I cannot find about it in issue or forum. If there already, I’m sorry to my poor search skill.

Version
Gitea: 1.21.5
Git: 2.34.1
OS: Ubuntu 22.0.4
rootless docker: 25.0.3

Compose

gitea:
    image: "gitea/gitea:latest-rootless"
    container_name: gitea
    environment:
      - USER=user
      - GITEA__database__DB_TYPE=postgres
      - GITEA__database__HOST=postgres-gitea:5432
      - GITEA__database__NAME
      - GITEA__database__USER
      - GITEA__database__PASSWD
    restart: unless-stopped
    volumes:
      - gitea_data:/var/lib/gitea
      - gitea_config:/etc/gitea
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro
    ports:
      - "7537:3000"
      - "6179:22"
    deploy:
      resources:
        limits:
          cpus: '1.00'
          memory: 4G
        reservations:
          cpus: '0.50'
          memory: 2G