Hi @Joostr
Could you try uninstalling the LastPass app, restarting your device, and reinstalling to see if that resolves the issue? If not, could you try Refreshing Vault and Clearing the Cache for your Vault on the app, then logging out and logging back in to the app to see if that works? You should find these options in the Settings > Actions area of the app.
This error is caused by a bug in the email field of the login. For some reason it is cAsE sEnSiTivE. Next time you log in, use all lowercase letters.
The solution was posted on reddit 4 months ago on a 7 month old thread.
https://www.reddit.com/r/Lastpass/comments/hek8sj/invalid_password_issue_android_10/