Where is the option to allow old RegEx logic? [duplicate]

I am not good with RegEx but i was doing good with semi-complex expression combinations while using http://buildregex.com/

However these expressions like this simple example: (?:b_)(?:.*)(?:\ \=\ \{)

(which would find stuff like b_somename = {)

are not working anymore and im curious if there is an option or settings.json entry to use the old logic without a rollback.

Thanks in advance