<< Solved >> Time Machine Backup fails although backup drive is 4x bigger

[EmanuelTheDude]

Hi, all of a sudden my time machine backups fail because of a disk space problem. I then removed the drive from time machine and erased the drive. Then I added the empty drive to time machine again as it was before.
The problem is that the backup fails with the message below. My hackintosh has a 500 GB SSD Samsung Evo and the external drive is a 2TB HDD from Seagate. I also tried 2 other external drives. One also has 2 TB and the other 500 GB (which is actually too small for permanent backups) of space. Both failed with the same reason like on the screenshot.
I excluded my Dropbox and Google Drive folder already.

 

[Edhawk]

How have you formatted the 2TB drive, HFS+ or APFS?

For a newly formatted 2TB drive the space available seems small at 1.44 TB, have you created another 400GB partition on the external drive?

 

[EmanuelTheDude]

On this particular drive I have some other data on it.

I found the problem yesterday. The new Android Studio update 4.2.2 came with a new Gradle update. Gradle has a hidden folder in my users root folder called .gradle. Time Machine thinks that this folder is 13,24 TB large which leads to the breakup (see the screenshot below). I don't know why this is possible on a 500 GB SSD?!
I excluded the .gradle folder and everything is fine now.