good news: theres a bypass to run old apps blocked by android 14 for being too old (targetting versions older than like Nougat or Marshmellow causes this)
Slightly irritating: It requires PC adb since the flag isnt present on the device shell.
"adb install --bypass-low-target-sdk-block"
this wont fix possible compatability issues but it will allow you to install the app without being stopped by the new restriction
Goo Truther 
@lyncia there is a magisk module you can load with root to bypass it untethered.
