Sorry to hear of your losses. Do you have a calibrated independent thermometer and hygrometer or are you using the thermometer and hygrometer that is 'built' into the incubator?
73% humidity is a little high for the final 3 days of incubation. I try to keep it around 60 to 65% , too high of humidity during lockdown can cause problems.
What was your humidity durning the 1st 14 days of incubation?
Your temperature was about right for 'still air' incubators. Should be 101° to 102°F as measured at the top of the eggs.
When you say they are dying in the incubator, is that after they hatch or while still in the shell?
How often are you turning the eggs?