Does it get worse as you progress from L3 -> L4 -> L5 -> L6 -> etc? Intuitively that seems like what would happen as your scope grows across promotions: Is there more overtime associated with the more senior levels?
Your intuition is correct: I've generally seen WLB get worse as you get promoted, largely due to the increase in scope, which leads to greater stress.
However, this trend isn't guaranteed. The reason it is this way is that people working at top companies in particular tend to be very ambitious, so they get promoted through a mix of behavior (ideal) and output (less ideal). So they are developing the behaviors needed at the next level, but they're also just working super hard. And if they remove the hard work, they could probably still survive at their new level, but it will be a bit shaky.
You can counteract this trend by pushing to get promoted in a healthier way that focuses more on developing deeper behaviors, particularly around prioritization. More concretely, this means putting limiters on yourself and still going for promotion. Work just 7-8 hours per day and try to achieve the impact of the next level with deeper behaviors and having a better sense around which projects to work on.