I use MSI Armor RX570 OC 8GB, and I had pretty good temps with 19.5.1 update all games maxed out and OC'ed with max power limit at 50% and I had 60c in all games!
Now I have 70c with Power Limit at 35%...
Also after thisd update max temp for my GPU went from 75c to 85c..
Should I rollback to 19.5.1?
Check if you have been switched to 10-bit color in Display options. That is more performance intensive for obvious reasons and could explain the extra heat.
Where a card begins to throttle is part of the silicon lottery. On my RX 580 mine begins to throttle at about 77. If you start noticing lag or stuttering in general that you did not notice before the extra temps may be causing throttling. At this point revert to a previous driver that worked or apply a custom fan and temp curve that kicks to fans up to max sooner. Either way make sure to let AMD know what is happening on you model: Online Service Request | AMD
Also peruse something like GPU-Z to detect throttling after setting constant clock - set all 5 top power states to same clock, disable states <= 4 and lock memory clock by setting min=max. Then you will see any throttling as a clock drop on any of SOC, Memory or GPU. Oh and mind you SOC voltage not memory voltage is controlled under Memory Voltage. You will have to raise it when overclocking memory or you get artifacting or memory throttling.
Typical cause of throttling is either thermal or power limit being hit. Power limit can be increased with a PP table mod if necessary, presuming you have the PSU and cooling to drive more wattage and don't mind the energy wasted.
I find the Polaris series since the Wattman drivers very unstable when you set static clocks. I find it much better to leave it dynamic as intended by the drivers. The power limit slider is already allowed in the Wattman page as it is. Yes setting it to it's maximum can very much help stability and I would recommend doing that in Wattman. I would not change anything beyond what you can do on the Wattman page, as doing so may be out of spec. AMD does not recommend changing these settings any other way. You also need not fear extra heat by setting it to max in Wattman as that setting is still in normal operating range. I would not pursue other settings outside the norm unless they don't work. Even then unless my card is out of an RMA period I would not either. If you card doesn't work in those parameters, the card should be warrantied.