Managed to do some testing with the new Kryonaut Extreme paste:
13900K Stock Cinebench R23 Run : 85 degrees / 311W - 40587 points
13900K Tuned LLC Level 3 (DC 1.1 / AC 0.28) Stock clocks Cinebench R23 Run : 77 degrees / 266W - 40251 points
In comparison my 12900K with TFX at 5.2Ghz all core ran at 92 degrees and scored 29426 points in Cinebench R23.
However, 2 factors that changed was I had to change the contact frame on my Z690 Apex as for some reason I just couldn't get proper contact so I installed the Feng Zao contact frame in Fibreglass material and that drastically improved my temps as above. I think that could also have been a reason why my 12900k ran warm when overclocked with the Intel stock ILM but right now this sits at around 15 degrees cooler than my 12900K with tuned LLC on both CPUs! And 13900k runs all core 5.5Ghz all-core for P-cores and 4.3Ghz for E-cores. 12900k in comparison ran 5.2Ghz all-core for P-Cores and 4.1Ghz for E-cores.
The other factor is that I changed my coolant brand to some newer one that's apparently better than EK Cryofuel. Seems less foamy and much much easier to bleed.
Pretty happy so far with this paste together with the contact frame mod. Everything runs nice and cool now and with tuned LLC, 13900k runs really nice and stable. Looped Cinebench R23 and R15 for 30 mins each to test stability. 0 crashes.