Looking all the way back on my list from 2016, I noted that those same four frequencies were all linked together. Now NAC 167, but 293 back then, as well as being 293 in my 2021 list.
To find my lists prior to 2012, I'd have to do some searching on the hard drive of my old XP machine. But I seem to remember the CTCSS of 167.9 being used on some of these frequencies. Probably the reason for choosing a NAC of 167.