I am using latest HitFilm version 2021.1
Facing a problem with image every time when I re open a saved project, image found flipped vertically without changing any attributes.
That's unusual. Try updating GPU drivers.
Otherwise, the forum is mostly users and this is the type of rate Glitch better handled through support. If a GPU update doesn't fix the issue, contact Support. They'll want to know your Hitfilm version, your system specs and your GPU driver version.