You might be troubled with various questions about your credit score. Consider your problem solved. There are different reasons why your credit scores change. You can explore these better and find more about them with help from a Credit Score Simulator, like the one you find in CreditKarma.com.
https://www.creditkarma.com/tools/credit-score-simulator
The Credit Score Simulator analyzes the information in your credit report. It can help you explore how the changes in your information or new credit card affect the credit score. This may be hypothetical, but it works and gives you an overview of what’s going on and how did things come to be. It may not predict future score changes, but at least you can have the answers to the what-ifs you have in mind. It allows you to get an estimate of the impact of the one action you made on your credit score or health. Overall, it’s a win-win situation for you. You get to learn about your credit score without taking any risk.
If you have further questions about how opening a new credit card account and other similar actions can affect your credit health, kindly refer to the abovementioned link.