I'm guessing (3). For one, I'm not sure that your observation is because you've gotten older and have become a more cautious driver, or if there is a quantifiable uptick in traffic violations. I also subjectively observed a behavior change right around the time COVID was declared a global pandemic and shelter in place orders were issued. At the time, I thought to myself that everyone was driving like they were in their own apocalypse movie.
A relaxation of police enforcement would likely result in driving behavior change, but it would be hard for us to quantify. Could be the result of increased immigration from countries with different driving attitudes. Could be changes to drivers ed. Could be a lot of things. Most likely it's our perception that has changed as we've gotten older.
I doubt it's cyclist who get in their cars and forget they can't run red lights though. I run reds on my bike because it's safer than waiting at an intersection (this is a demonstrable fact, before anyone replies how much they hate me and my kind or how unfair or yada yada). What I don't do is carry that behavior over when I'm driving a car. I'm in a completely different mode.