Your plant looks healthy, I've read your giving bloom nutrients and cal mag, It is too early!! You should give grow nutes during vegetative and correct your pH to 6.0
Be patient, don't run too much and you will surely get a lot of satisfactions :) Good luck with your grow ☀️☀️
This is caused by the pH being out of range or too much fluctuation. If you are in soil you want to shoot for a pH of close to 6.5. if you are in soilless then shoot for 6. Good luck!