There could be multiple reasons.
Step 1: Check to see if your QR Code has an 'expiration date':
Click "Edit" on your QR Code
Go to the "Customize" tab
Scroll down to the Advanced Options section.
Step 2: Check to see if your QR Code was flagged for spam:
Uniqode maintains a blacklist of phishing URLs that is continuously updated. Whenever a website URL is linked to a QR Code created on Uniqode, the phishing URL detection framework cross-references it. It disables any QR Codes that are associated with malicious websites immediately.
If you’re receiving an email about Uniqode automatically disabling your QR Code, it means that the QR Code created in your account was leading to a malicious link. This email will also contain instructions to update the malicious URL attached to the QR Code with a valid link.
Note: Any account found creating phishing QR Codes repeatedly will be disabled and deleted at the discretion of the Uniqode team.