We want to increase our conversion rate, so the marketing team suggests to use the pattern when information is locked before the customer clicks CTA. I actually don't know how this pattern is called and if it's a promising idea, so I'll appreciate any information about your experience, some reading or research, thoughts. Is it considered as a dark pattern?
"Read More" CTAs are used on article/news sites to help determine if users are just opening the article, or if they're actually engaged enough in it to continue reading the rest.
In the example above, the CTA given may not be the best option. If they're looking for the graph and already have access to it, this is just slowing down how they're retrieving their data, while "teasing" them that it's right there.
An alternative to get any click-through you may need is instead a button that says "Open Charts", then the chart appears on the same page. So that it's like the user is loading in the chart after visiting the page. Another alternative would be to just have the chart on a separate page, and then you can track page visits.
If the user does not have access to the charts and you're trying to get them to upgrade and buy it, changing "Unlock Charts" to "Upgrade to Unlock Charts" may be more descriptive and allow the user to know what they're clicking on.
About whether or not it's a dark-pattern depends on how it's implemented in this case. If they have access, but you're just hiding it from them, that doesn't help the user and obscures their access to your product from them. By using my suggestions in those cases it may seem less like you're just hiding things for no reason and instead need an extra button click/page visit to load the information for the user. If they don't have access to the chart, re-wording the unlock button to be more clear of where they'll be taken or what it will do may help. Additionally, the graph behind the overlay shouldn't be the actual graph (because they could just look through it) and could just be a blurred out fake graph to prompt them to see what may be there.