if refer to the 802.3at, it should can provide up to 30Watt for the port.
But, refer to the technical spec for https://mikrotik.com/product/RB960PGS.
Max out per port output (input > 30 V) 450 mA, meanings this is only if ,
1) 48 VDC x 450mA = 21.6 Watt.
2) 48 VDC x 450mA = 22.5 Watt.
so, it cannot support 802.3at as min is 25.50 W for this standard.
Please correct me if i am wrong.