Does anyone feels that the level of difficulty in DILR for CAT 2020 slot 1 was lower when compared with slot 3?

you are wrong. Slot 2 DILR was the toughest. Slot 1 and 3 had a venn diagram set which could have fetched 12 easy marks. SLot 2 DILR was insane. Slot 3 also had another doable set with the medicine vials. And Quant was easy in all 3 slots.

slot 2 dilr was insane for sure

of course, Slot 3 's DILR was the toughest.
It was the case with slot 1's VARC and Slot 2's Quants if I am not wrong.

slot 1 dilr easiest and varc toughest
slot 3 dilr toughest
overall slot 3>slot1>slot2