If you're unaware, starting August 2021, Netflix had started cracking down on DNS and VPN providers. This was done in order to prevent access to geo restricted content due to tremendous pressure placed on Netflix by content producers
Initially, this issue was affecting U.S. based geo restricted content for the U.S. However, as time progressed, it starting affecting all regions. As a result, when connected to the VPN, you will only have access to Netflix Original titles.
How Netflix achieves this is a two step process. The first thing done by Netflix is a comparison between the geographical information associated with the method of payment against the IP used to access the service. If the information does not match, you will only be presented with Netflix Original titles. For instance, if you had used a U.S based credit card for your Netflix account and were trying to access with a U.K. based IP, Netflix will detect the mismatch.
The second thing done by Netflix is an IP check against certain databases. A lot of web services such as online gambling, financial institutions, and etc are tied into certain IP databases. These databases provide generic information about the IP such as IP geolocation, hosting providers, and etc. If Netflix is able to determine that the IP being used to access their resources belongs to a VPN and or proxy provider, you will have access to Netflix Original titles only.
We are working on a few solutions to bypass this issue but, due to the complexity of the issue and solutions required, it will take some time. Rest assured, this matter is being actively looked at.