Why is Vivaldi is taking up over 100gb of disk space?

[moshbit]

Not sure why, but my Vivaldi browser is taking up over 100gb of disk space on my laptop. Using Windirstat, I am able to drill down the source of those files to the folder here:

C:\Users\Administrator\AppData\Local\Vivaldi\User Data\Profile 2

It seems there's a series of numbered folders there, each containing around 1gb of data. Each folder has a series on numbered files around 8 mb a piece:

What could be causing this and how do I fix it?

[iAN CooG]

@moshbit The "File System" folder should get emptied each time the browser is closed and reopened, at least for me each morning is empty, but after downloading for example from mega.nz the files gets copied there before downloading. Manually deleting from time to time the "File System" folder is perfectly safe as it's just (another) cache folder for chromium browsers, that indeed clutter temporarily the HD during the browser usage.
Out of curiosity, when is the last time you have actually closed Vivaldi? Do you by any chance always keep your laptop on with all the programs active?

[moshbit]

I do keep my laptop on for long periods of time, but I tried closing and reopening vivaldi, and clearing the cache and the files are still there. You're most likely right though about mega.nz, I did download a boatload of stuff from there recently, and I know their downloader does store the data in the browser before copying it over to the downloads folder, but this is the first time I've had a problem with the temp files not getting removed.