Does cloud storage count as a backup?

Not by itself. Synchronisation and backup solve different problems, and the difference only becomes visible on a bad day:

• Sync mirrors mistakes - delete or encrypt a file locally and the change propagates to the cloud copy within seconds.
• Backup keeps history - it lets you go back to how the file was before the mistake.
• Version history helps, within limits - many services retain 30 days or so; ransomware and slow-burn corruption can outlast that.

If your only copy is a synchronised folder, you have redundancy against hardware failure and nothing against error or malice.