The change of contacts display does impact how my email senders are named. I had the goofy issue with 14.2. Many other threads on this issue, several noting the problem only in inbox and not other folders so clearly a bug not intended. I don’t know why contact display order impacts mail senders, including many not in my contacts (likely the case fir the vast majority of iPhone users), but it clearly does. However, if I change sort order in contacts, as with others, I also have the first, last display in contact as well as mail. So mail senders read normally like they used to but contacts is harder to read because first name is displayed first which, to me, is visually confusing and makes it harder to find what I’m looking for.
I will note that after changing the display order to first, last and seeing the mailbox senders fixed, I tried changing sort order in contacts back to last, first and found that, while contacts reverted to my long-standing and preferred display of last, first, the mail sender display did NOT change back to the weird last, first order that took over with 14.2. This is good. I quit the mail app and relaunched and found it has retained the corrected sort order. I have changed it back and forth several times in preferences and, since changing it back the very first time, changing contact display preference has ceased to effect how mail senders are displayed. No matter what I set display order to, only contacts change (as one would expect), but not mail sender display, which stays “normal”, for lack of a better term.
Don’t know how long it will last (hopefully permanent), but for the moment I have the display order I want in mail and the one I want in contacts and the preference to change sort order is now only changing the display in contacts with mail unchanged since the first change to correct it. Clearly and unequivocally a bug.