This is actually per design, as you usually want also a different value when using a different key. So leaving the same value will lead to more problems. So when you change the field - then you you also change the value.
Personally for me this doesn’t work like that but maybe my brain is an outlier.
I often duplicate these actions and have in my mind what I want to do. So I change the key and the value in no particular order. And apparently I very often change the value first, then I change the key, and then I have to change the value again
Perhaps other people can chime in if this also bothers them? If it’s just me I’ll adjust