Apple

30 GB in a backup takes a while, but it is also generally not a good idea. The bigger a file is the more likely that sometime during writing the file something goes wrong. I would recommend moving as many files as possible outside the backup ( enable sync instead for iCloud Drive, Photos, WhatsApp backup etc. that still requires the same iCloud space, but instead one big long process you have many tiny ones. That’s much safer and much less complicated.