Same problem here. As i suggested in another thread, you really should remove the Joomla4 support from your website, to protect other users, run into this problem. And also to protect you from getting trouble with lawyers from companys who buy this for joomla4.
@spooks: I don't know if its helpful but when i upgrade a site from joomla 3 to 4 (with already installed BF), my forms are working and could be used. They Layoutproblems in the Backend are the same.
@tihana We will need to use Joomla 4 for new Websites, because of some important features. Thats why stay on J3 is not an option.