A brief blog about AB333, which created Penal Code 1109, and revised Penal Code 186.22: This bill enacted laws that changes the rules for gang enhancements. Basically, when the prosecution wants to prove that the crime was done for the benefit of the gang, they have to prove that it benefited the gang in some way more than reputational gains (i.e. it must be financial gain, retaliation, etc) The prosecution also must prove that the defendant is part of a criminal street gang which requires proving there are prior convictions from members of the same gang (called "predicate offenses"). Previously, the crime being currently charged can be used as a "predicate," but under the revised laws, that's not allowed.
Most importantly, a published decision just ruled that all of these changes are retroactive, BUT ONLY to those whose cases are not final. (see the published case here) These means it applies to someone whose case is STILL ON DIRECT APPEAL, or someone who is being fully RESENTENCED. But it does NOT create an independent way to request resentencing or reversal.
So if you're getting resentenced pursuant to 1170.95 (aka SB1437/SB775), or 1170.03 (formerly 1170(d)), or pursuant to SB483 (PC 1171/1171.1, the removal of certain prison and drug priors), then AB333 will ALSO allows your lawyer to try to get the gang enhancements removed, by arguing that they are not proven under the new law, and must therefore be stricken from the sentence.