When there is a project resolution change the compositions/effects are not correctly "resized"
Create a Project 1080p place a clip with "composition and transform" and resize it... after that swithc project settings to 4K, and the coordinates used on compositions are not changed to better fit the new project resolution (not saved as a % of screen... but as just integers.. and maybe this need a "conversion" of the project)
original bug report of 2017: https://bugs.kde.org/show_bug.cgi?id=385797
and this using an effect: