If you’re really paranoid, download a 2nd copy and put it on a hard drive that you then leave unplugged from all computers and the internet until the next time.
Simple solution for anyone with broadband, and then if you ever lost your cloud data due to subscription lapsing or inactivity you have 1-2 local copies for you or your family.
"Export 1 of 1 will start on 18 November 2020"
Any idea what I'm supposed to do about that?
Use the 3-2-1 backup method (3 instances of data, 2 of them not the original (backups), 1 of them offsite). I use cloud backup(s) for my offsite(s) and the remaining backup lends itself to being an external harddrive (or a very well firewalled NAS if it must be on the network).
In general, it's good security practice to keep a set of backups offsite, and disconnected.
As someone who does this every month, the downside is that there are often glitches in the export (which they usually catch) and you'll need to set up a new export to get them to try again. In the worst case, I've needed to re-export three times to get them to green flag it as a clean collection without any errors (which sucks when it's a couple days for them to prep it and then another while to actually download and store 300GB of data).