UserWarning: This pattern is interpreted as a regular expression, and has match groups

Question

Given the following pandas DataFrame -

json_path	Reporting Group	Entity/Grouping	Entity ID	Adjusted Value (Today, No Div, USD)	Adjusted TWR (Current Quarter, No Div, USD)	Adjusted TWR (YTD, No Div, USD)	Annualized Adjusted TWR (Since Inception, No Div, USD)	Adjusted Value (No Div, USD)	TWR Audit Note
data.attributes.total.children.[0].children.[0].children.[0]	Barrack Family	William and Rupert Trust	9957007	-1.44				-1.44
data.attributes.total.children.[0].children.[0].children.[0].children.[0]	Barrack Family	Cash	-	-1.44				-1.44
data.attributes.total.children.[0].children.[0].children.[1]	Barrack Family	Gratia Holdings No. 2 LLC	8413655	55491732.66	-0.971018847	-0.971018847	11.52490309	55491732.66
data.attributes.total.children.[0].children.[0].children.[1].children.[0]	Barrack Family	Investment Grade Fixed Income	-	18469768.6				18469768.6
data.attributes.total.children.[0].children.[0].children.[1].children.[1]	Barrack Family	High Yield Fixed Income	-	3668982.44	-0.205356545	-0.205356545	4.441190127	3668982.44

I try and save only rows that contain 4x occurances of .children.[] using the following statement -

Code: perf_by_entity_df = df[df['json_path'].str.contains(r'(\.children\.\[\d+\]){4}')]

However receive the following:

Error:UserWarning: This pattern is interpreted as a regular expression, and has match groups. To actually get the groups, use str.extract.

Any suggestions why this is happening?