Welcome to the forum & congrats on 1st post. Never heard of this issue, you mean the option is literally not available as it usually is while posting a video?
did you try to export these same videos in 1920*1080 just to see if end screen works? will you loose a lot of valuable visual information?
sorry but it's not possible
View attachment 44642
but most people don't have that aspect ratio anyway??? that is pretty niche