Save macOS screenshots in ~/Pictures/Screenshots/YEAR/MONTH/

com.nextcloud.screenshots.location.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>

    <key>Label</key>
    <string>com.nextcloud.screenshots.location</string>

    <key>ProgramArguments</key>
    <array>
        <string>/bin/sh</string>
        <string>-c</string>
        <string>d="$HOME/Pictures/Screenshots/$(date +%Y)/$(date +%m)"; mkdir -p "$d"; defaults write com.apple.screencapture location "$d"</string>
    </array>

    <key>StartCalendarInterval</key>
    <dict>
        <key>Minute</key>
        <integer>0</integer>
        <key>Hour</key>
        <integer>0</integer>
        <key>Day</key>
        <integer>1</integer>
    </dict>

    <key>RunAtLoad</key>
    <true/>

</dict>
</plist>

install.sh

# prerequisite: install python3 and grant it full disk access
# System Preferences -> Security & Privacy -> Full Disk Access -> [+] -> /usr/bin/python3

url=https://gist.githubusercontent.com/qguv/2f83bcbea302b12f35bfeef56f33272a/raw/4f14a8acec56c754387bf2f585a9546c64506b14

# unload existing agents if present
launchctl unload ~/Library/LaunchAgents/com.nextcloud.screenshots.location.plist 2>/dev/null
launchctl unload ~/Library/LaunchAgents/org.mozilla.firefox.screenshots.location.plist 2>/dev/null

# download + install new nextcloud agent
curl \
    -o ~/Library/LaunchAgents/com.nextcloud.screenshots.location.plist \
    $url/com.nextcloud.screenshots.location.plist
launchctl load ~/Library/LaunchAgents/com.nextcloud.screenshots.location.plist

# download + install new firefox agent
curl \
    $url/org.mozilla.firefox.screenshots.location.plist \
| sed \
    "s@/Users/qguv@$HOME@" \
    > ~/Library/LaunchAgents/org.mozilla.firefox.screenshots.location.plist
launchctl load ~/Library/LaunchAgents/org.mozilla.firefox.screenshots.location.plist

org.mozilla.firefox.screenshots.location.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>

    <key>Label</key>
    <string>org.mozilla.firefox.screenshots.location</string>

    <key>ProgramArguments</key>
    <array>
        <string>/usr/bin/python3</string>
        <string>-c</string>
        <string>

import os
import pathlib
import shutil

downloads = pathlib.Path(os.environ['HOME']) / 'Downloads'
screenshots = pathlib.Path(os.environ['HOME']) / 'Pictures' / 'Screenshots'

for src in downloads.glob('Screenshot *'):
    try:
        year, month, _ = src.name.split(' ')[1].split('-')
    except (KeyError, ValueError):
        continue
    dest = screenshots / year / month
    dest.mkdir(parents=True, exist_ok=True)
    print("moving", str(src), "to", str(dest))
    shutil.move(str(src), str(dest))

        </string>
    </array>

    <key>WatchPaths</key>
    <array>
        <string>/Users/qguv/Downloads</string>
    </array>

    <key>RunAtLoad</key>
    <true/>

</dict>
</plist>