Since many have had/are having the same problem as me, I will list the steps I took to get the same result as shown in the lesson.
Let’s start from before deleting the UV Map, when we apply “Seams from Islands”:
- Select all the UV → UV menu → Seams from Islands
- Delete the UVMap in the Object Data Properties → UV Maps
- Press U
- By focusing your mouse on Unwrap you will see another menu
- Select Angle Based
- Tadaaaaa. It will be all like in the video lesson.
If you do not follow the procedure step by step you will never get the same result that is shown in the lesson. So if you do not get the same UV Map shown in the lesson it is very likely that you have skipped some steps. My advice is to go back to step 1 and follow to the letter what is explained by Grant: that is, the steps that I have transcribed above.