Just a few thoughts for consideration ...
Rochester / Beauty - given that an unbanded female moved into the nest with Beauty's new boyfriend the day after does raise the likelihood that her death was related to a territorial dispute - most of conflicts don't happen in the nestbox and given where these peregrines live, we only see a very small portion of their lives. Princess had a heck of a fight close to a decade ago, one she spent 3 days hanging out inside the nestbox recovering from - she'd never stayed in the nestbox without eggs/young chicks before. She limped for quite a while and she had cuts/abrasions on her head. At 15 she would have had a hard time matching a younger bird.
Warren Michigan female - no idea here of course, but Pop disappeared one day mid-incubation. His son T-Rex abandoned his mate in South Winnipeg and moved in downtown with Madame to raise his father's four (if I remember correctly) chicks. It was like they were his own kids, smoothest transition ever. T-Rex never went back to his old mate, she eventually moved to another site closer to downtown. Holly's mate Zeus vanished not once but twice for a year each time from the McKenzie Seeds site. Returned to pick up where he left off except in his last year when he was replaced by Brooklyn. (Brooklyn hatched in Brandon during one of Zeus's sabbatical years). We've also had a few younger females go missing - most recently Marilyn in 2020, Etta in 2021 - they were here, then they were gone and they were not replaced by other females. No point in speculating what happened until there is perhaps more news ...
Omaha / Chayton - she was younger but we are a little lucky to have longer lived birds here - the average age for a wild peregrine is 5-7 years, so she was "older". Her death is definitely a mystery, could be she was injured (fight or collision or ??), bacterial infection, viral infection, response to something toxic (not particularly likely) or maybe something like Taku's stroke-caused brain damage - no cause, just happened. But H5N1 is a concern particularly for domestic birds so understandably folks would be concerned. Again, may just have to wait and see ...