Grep: pattern_2 NOT preceded by pattern_1 (with pattern_1 not necessarily IMMEDIATELY to the left of pattern_2)

Hello everyone. I would like to craft an expression to find lines that contain pattern_2 NOT preceded by pattern_1 (with pattern_1 not necessarily IMMEDIATELY to the left of pattern_2). This is the catch, so let me repeat it with emphasis on IMMEDIATELY: with pattern_1 not necessarily

[ANN] BBEdit 12.5 (411033) pre-release

Good morning folks, We're currently working on a feature update to BBEdit 12, which includes a number of new features, as well as fixes for previously reported issues. Testing is currently underway, and we have a stable pre-release version ready for use. Note that this is a _pre-release_