VPN needs to be turned off to access some websites

Yes, there's more to the story here. Some websites or services may block or restrict access from certain VPN servers or detect and disallow traffic coming from known VPN IP ranges. This especially happens with banking, streaming, or high-security sites that block connections from IP addresses known to belong to VPN providers. This is typically an anti-fraud or anti-piracy measure. Then, a website might only be accessible from certain regions. By enabling the VPN, you appear to be coming from another country/region, which is blocked. Some streaming platforms strictly enforce region locks, so you may need to disable the VPN or find a location that matches the service’s supported region.

There could also be DNS or IP conflicts involved. If there is a DNS misconfiguration, you could fail to connect to certain domains. You could try to flush DNS. On Windows, open Command Prompt as administrator and run ipconfig /flushdns. Also, you can temporarily set your DNS to 1.1.1.1 or 8.8.8.8 (Cloudflare or Google) in your network settings to see if this fixed the issue.

This article may also prove useful and you can try these instructions as well:

https://www.bitdefender.com/consumer/support/answer/30765/

If nothing helps, the root cause could be more difficult to track, and in this case more information might be required for troubleshooting. You can resort to contacting the Bitdefender Support teams, should you require further technical assistance with this. Here's the link you can use to get in touch with them:

https://www.bitdefender.com/consumer/support/help/

State your contact reason / choose request category, then choose from the available contact channels, chat, phone and email/ticket. Chat would be the fastest way to reach them.

I hope this helps and let us know how it goes.

Regards