Hello,
I have the same issue with multiple SharePoint sites. All are switched automatically to the List view, and their customazed forms (Size Large in Landscape), are opening in a very small window. People have to scroll multiple times to fill them in.

Please someone advise what can be done!
Thanks

We're seeing the same behavior here. Users are getting frustrated, especially since we just started rolling out PowerApps on SharePoint within just the last few months and worked through multiple issues to get to this point.

If not fixed we'll need to move out of SharePoint Lists

I was able to provide a work-around (though users are a little confused about it) by adding some column formatting with a button that opens the list item in a new tab using DispForm.aspx (EditForm.aspx would not work; it doesn't save the changes).

The button's attributes are like this:
"target": "_new",
"href": "='https://company.sharepoint.com/sites/SiteName/Lists/ListName/DispForm.aspx?ID=' + [$ID]"