Hello!
For everyone having issues with the nextcloud desktop app while uploading big files I found a solution for it.
After reading the docs and forums multiple times I finally found a solution.
Of course you have to first modify your nextcloud instance to accept big files.
Then you need to check the docs of the desktop app and modify the maxChunkSize parameter. After I reduced it to 50MB I was able to upload big files.
I don’t know why this option was setted by default at 5GB.
These are the sources that I followed.
nextcloud set up This configuration only works with web uploads
Another configuration parameter This is for desktop apps found in here
Good luck!
Edit:
Forgot to mention that the file upload was tested with a 10GB and 16GB File. both of them work, as I setted up the limit at 16GB it will not accept bigger files.