https://www.criminaldefenselawyer.com/resources/criminal-def...
https://www.shouselaw.com/burglary.html#2.3
I'm not a lawyer so here's how I interpreted these lawyers:
Petty theft is up to six months in jail + up to $1,000 fine. Prop 47 added a misdemeanor shoplifting statute with a max. incarceration to one year. Previously this was considered burglary where a defendant could be charged with either a misdemeanor (up to a year in jail) or felony (up to three or so years).
The existing burglary statute (which otherwise covered what is now called shoplifting) carries a sentence of up to one year in jail (misdemeanor) or more (felony). The gangs taking less than $950 worth of goods are taking advantage of police apathy. So, sure, maybe Prop 47 resulted in an increase in shoplifting/burglary. However, if the police were to see these things through repeat criminals would still be subject to the same felony statue as before.