Hi @Bnilath,
Thank you for your patience.
We've been able to reproduce the issue and investigate with the files you've shared with us. The short answer for what's happening is that the "exploding text" results from font-substitution for a missing Arial Narrow font.
Unfortunately, Microsoft has stopped including Arial Unicode MS fonts in Windows 10.
If you're running Windows 10 and you have this font installed, then it's either from an older version of Windows you've upgraded, or from an installation of some software / paid extension.
When you upload a DWG file to BIM 360, it gets processed in Autodesk's cloud service, and if the machine where it's being processed is missing a font, it would replace it with some default fallback (Simplex.shx).
Unfortunately, it seems to be outside the control of AutoCAD, BIM 360, or Autodesk, so it will be up to users to choose a different font that's available in clean version of Windows.
Here are a few additional links on the subject:
To work-around this issue, please try changing the font in the original DWG to a font that's available on a clean Windows 10 installation, and you should see the same font when you upload to BIM 360.
I hope this helps.
Best Regards,
Doreen