Having phosphates that high will just lead to algae issues. However, if your CO2 levels are sufficient enough, this could outweigh the potential algae causing effects of the phosphorus. Have you ever tested your phosphate levels in the aquarium without EI dosing? You may not need to dose KH2PO4 at all if your natural phosphate level is around 4ppm (your nitrates are at 40ppm so the recommended 10:1 ration of nitrate to phosphate would lead to a 4ppm phosphate level). I would recommend stopping KH2PO4 dosing after your next water change and seeing at the end of that week how your Phosphate levels have responded. If they stay at 4ppm or higher I would stop dosing KH2PO4 (make sure to dose more K2SO4 to make sure there is sufficient potassium) however, if your levels are lower than 4ppm after that I would try and find the magic amount of KH2PO4 you need in your tank to manage a level that is ~4ppm phosphate. I had this same exact problem in my 36 gallon planted bowfront and never dose phosphates because my phosphate levels are naturally high without dosing. A few SAEs and a BN pleco take care of any algae that may result of the high phosphate levels as I do not CO2 inject.