Regarding the high levels of overtime worked (upwards of 500 hours or 60 shifts/year in one of the remaining stand alone TCU's), Many had hoped that Covid would be the reset that most ATC's would need to realise that time away from work, spent with family and friends was far more important than propping up a failing (failed?) system. Unfortunately that old habits are hard to break and perhaps big capital city mortgages drive so much of the decision making, but it appears that little has changed.
In term of CASA/ATSB investigations, sadly both organisations seem to have a number of ex ASA managers within their realms. I will let you decide what effect that may have.