the correct Cohen D formula for paired ttest

I have read some articles and I am not sure which is the best way to calculate the effect size for paired ttests. According to this Geff Cumming paper, using the pretest SD is the best way to go about it.

d = mean(paired_differences)/pretest std

Another formula I have stumbled upon is

d = mean(paired_differences)/std(paired_differences)

Can someone help me with understanding how they are different? For context the data I have is paired samples for pre and post intervention