I have set up a scheduled backup under Configuration > System > Scheduled Backup Settings.
However, I don't know why but the system seems to be doing three backups at the same time.
This is causing a strain on the server.
Is there any way to stop them all and start afresh?
You can use this free script to back up your store https://blog.amasty.com/how-to-backup-a-magento-store-tutorial-script/
Also, check out this extension https://amasty.com/magento-cloud-backup.html , it may be helpful