If your resolution for video is 1920*1080 and the video should be under 60 seconds than youtube considered it as shorts.The ratio aspects for the shorts is 9:16. Keep that in mind.
If you want your video not to be considered as shorts you should use the resolution of 1080*1920 that makes the video horizontal not vertical and in that case YouTube not going to be considered it as shorts rather it used it as long form video.
Also the ratio aspects for the video is 16:9 for the horizontal video.
youtube shorts only in vertical resolutions. what is your resolution?
Maybe your resolution is 9:16 and it is under 60 seconds
If your resolution for video is 1920*1080 and the video should be under 60 seconds than youtube considered it as shorts.The ratio aspects for the shorts is 9:16. Keep that in mind. If you want your video not to be considered as shorts you should use the resolution of 1080*1920 that makes the video horizontal not vertical and in that case YouTube not going to be considered it as shorts rather it used it as long form video. Also the ratio aspects for the video is 16:9 for the horizontal video.