Screen Time is not an accurate indicator of Battery Usage for any sort of comparison. Of course Meta is going to be using your battery, and that occurs even when you are not using your device. They let you use their app for free in exchange for the data harvesting to sell your activities to advertisers. You are the product being sold and that is how they report billions of dollars in revenue each quarter. Compound that with the frequency of the Meta updates to continually resolve bugs introduced in a previous update and you can see how that cycle continues.
You can post the screenshot at Settings > Battery > View All Battery Usage and include the 2 battery graphs and the top 6 apps consuming your battery. That will be much more informative than any Screen Time value.
Also after an update, you should expect background processes being performed on your phone that will drain the battery and produce extra heat for about 4-5 days after the update. To ensure those processes are allowed to complete after an update, it is best to plug your phone into power and connected to WiFi all night, every night and use the Optimized Charging option. If you are seeing a high level of battery usage under the Home & Lock Screen category, that is a good indicator that those background processes are still being performed.
As far as testing the apps, it is simple to uninstall them and compare your results. During that time while the app, such as Instagram, is not on your device you can access that service on the web using Safari and that will not drain as much of your battery as using the app.
