There have been cloudflare problems affecting at least FR24.
So that might be part of it.
You can change the systemd service for FR24 to actually produce useful logging information instead of just spamming:
Backup and edit /etc/systemd/system/fr24feed.service:
sudo mv /etc/systemd/system/fr24feed.service /root/fr24feed.service
sudo nano /etc/systemd/system/fr24feed.service
Paste the following:
[Unit]
Description=Flightradar24 Decoder & Feeder
After=network-online.target
[Service]
Type=simple
Restart=always
ExecStartPre=-/usr/lib/fr24/install_dump1090.sh
ExecStartPre=-/usr/lib/fr24/create_missing_directories.sh
ExecStart=/bin/bash -c "/usr/bin/fr24feed | sed -u -e 's/[0-9,-]* [0-9,:]* | //' | grep -F -e imeout -e rror -e info -e main -e onnect -e reader --line-buffered"
User=fr24
Group=fr24
PermissionsStartOnly=true
StandardOutput=syslog
SyslogIdentifier=fr24feed
[Install]
WantedBy=multi-user.target
Ctrl-O and enter to save, Ctrl-X to exit.
After saving the file:
sudo systemctl daemon-reload
sudo systemctl restart fr24feed
sudo journalctl -u fr24feed -f
Now if you get the mail from FR24 you can do this:
sudo journalctl -u fr24feed
That will give you at least some information what the feed client was doing at the time.
But my guess: nothing to do with you.