Issue with changing of brightness of screen with Function keys

[ I am using i3wm]
I earlier had the common problem as most have here. Function keys did not work for changing brightness.
But i worked on the issue. and fixed it.
What i did there was exactly as stated here:

But here is another issue with that. I have set brightness to change in steps of 5%.
But when i use function keys to change it. The change is random. like:
For the first key press. the brightness decreases from 100% to 89%

For 2nd keypress, changes from 89% to 79%

Then to 69% to 59 to 49 to 33 and so on… I mean the values are random…

and when i increase it, it again increases randomly. like from 33% to 44% to 54% to 64% like:

All i want to know why is the change so random? and why it doesnt change in steps of 5% as written in script

NOTE: I am using brightnessctl. and also when i directly use the brightnessctl via terminal, the change is consistent with the specified change percentage.