Looks like Boron deficiency, any other idea?

After my last watering with BioBloom, BioHeaven, CalMag, and TopMax, these rusts occured in 1-2 hours. Only on newer growths. As far as I research, it seems B deficiency but before i take any action, i need to be sure.image2.jpegimage4.jpegimage3.jpegimage1.jpeg

Soil: BioBizz Light Mix
Temp: 21-28c
Hum: 40-65
12/12 light
1st week of flowering.
Only super cropped the stem last week. No other LST or HST done.

Same rust happened 2 weeks ago on a fan leave but was only on one leave; so I didn't mind that.
 
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