If you're just now making the jump from an Intel-based Mac to Apple silicon and you use Migration Assistant, you should be aware that if you have a old trail of installs on certain packages (Dropbox and iTerm2 are two) that followed you from previous profiles, you might be in for trouble.
Trouble takes the form of a pop-up warning you that at support is ending for Intel-based apps, and that this version of "ProgramName" will not open in a future release of macOS. If whatever you're using runs automatically every 20 minutes -- looking at you, DropboxUpdateClient -- you will see a lot of these things.
If you are absolutely positively sure you have updated to the Apple Silicon version of whatever-it-is and support is telling you to do things like make a new profile and use it whenever you want to use the app, here's your last resort:
You want System Report, via Apple menu. Then:
- About This Mac
- More Info...
- About
- System Report (a gray button at the bottom of the About section)
Once you make it into System Report, open up Software and then Applications. The far right column is Kind; click it to sort and then scroll down and look for Intel.
These are the ones that may trigger the pop-up if they run. Caution: messing around here might mess up your system if you don't know what you're doing.
Here's a much longer Dropbox thread about this issue, in case it's what you're looking for:
Thanks so much to the hero with the throwaway account name who clued me in here!