Bed is leveled and not warped but still uneven printing?
Be sure that you have no previous bed meshes saved and automatically applied: use the commands M502, M500.
Once you have done that, try this technique:

                
            
It's about using a ruler to detect areas which are lower, and then use stickers below the glass to thicken those areas only, resulting in a much flatter surface.
If you don't want to use the blue tape (which will worsen the heat transfer, but not so much after all) you could use 0.3 mm silicone thermal tape, which is more heat conductive but it's also quite thicker than blue tape.
This other alternative consists of flattening the plate itself, but it's inevitably performed when cold, while the tape technique above can be performed at the desired temperature (since the warping may not be constant).