Thank you.
Current Texture size limit is 512 x 512 px. This limitation is just because of the godot 3.3 version, streaming currently a lot of high res textures frequently (while drawing) is currently a bit slow in godot and i don not have, as far as i know, directly access to the opengl functions in godot.
This will be much better with 4.0 and Vulkan ,i hope.