I just wanted to note that I have encountered an issue similar to the one mentioned here (https://powerusers.microsoft.com/t5/General-Discussion/Auto-height-bug/td-p/164437), where I'm noticing that controls (in Galleries and Forms) are not displaying text correctly when visibility is set to be conditional, and auto height is on. Turning off the new "improved rendering" option seems to have resolved this issue.
FYI turning off "improved rendering", at least for us, only reduces the change of this bug still happening. We still get it occasionally.
I created a powerApps idea to hopefully bring some attention to it, please kudo it if you would also like to see it fixed: fix auto height please. : )
Currently, there still have some unknown issue with the "Improved app rendering (final validation)" functionaltity within PowerApps, the PowerApps Product Team is investigating this issue.
If you faced this issue again, please consider take a try to disable/turn off the "Improved app rendering (final validation)" option within Advanced settings of App settings to display/render your app in a classic mode to fix this issue.
I personally still have the same problem at the moment.
The deactivation of "Improved app rendering (final validation)" remains the only solution at the moment.