This isn't yet supported from the account page (it should be at some point), but there is a workaround. It you navigate to your user profile elsewhere in the app, for example by searching for yourself or tapping your username on a post/comment, then scrolling should hide the banner as you expect. Hope that helps!
Thunder App
An open-source, cross-platform Lemmy client for iOS and Android.
This community is intended to discuss features and feature suggestions for Thunder; as well as friendly, respectful talks about Lemmy in general.
Please use the GitHub repository linked below to submit bug reports, so keeping track of them is easier, and make sure to search first if you already can find an issue for your report.
If there are any developers who would like to contribute, feel free to reach out on GitHub!
General Links
Website: Link
GitHub Repository: Link
Matrix Space: Link
Android Releases
IzzyOnDroid: Link
Google Play: Link
iOS Releases
Apple App Store: Link
TestFlight Beta: Link
Related Communities
Nightly Community: Link
I can't answer your question, but maybe your phone has an option to make long screenshots?
It probably does but it’s still an inconvenient app feature.