Bathroom wooden floor needs leveling

[postie]

Hi all
Got a bathroom floor to do soon ,the plywood is already down but there is a high spot in the floor near the edge ,when puting my spirit level across the floor from the high spot i would have to raise the floor to almost 20 mm to keep it level with the edge.
Question is will it be ok to raise the floor up with SLC on a wooden floor by as much as i need to . or would it be ok to start tiling at the high point and have a slight angle on the edge tile towards the middle and then carry on tiling the rest of the floor as the floor is ok bar this high spot at the edge.

 

[Turkish]

What`s causing the high spot? Can you not take up the ply and see if it`s something you can remove from underneath? If you just tile from it you are gonna be eating through adhesive like nobodys business and 20mm is a big adhesive bed!

Turkish