Effect of lone 30D aging off

For several years, the only baddie on my file has been a 30D from November 2017. I tried to get it removed with goodwill letters a while back, but the creditor, Capital One, wouldn’t budge. Conventional wisdom says it should have stayed on my file for seven years, and by the end of that time its effect on my scores should be moderate. Here’s what actually happened. Transunion The 30D mostly vanished 49 months after appearing. I say “mostly” because there were still a few scores that reflected a missed payment. For example, all my TU10s still have it. They must look at a different indicator than the older scores. When it dropped off, my F8 score gained 33 points and my mortgage score also gained 33 points. Experian The 30D vanished completely in month 80 (i.e. 4 months before the 7 year mark). Seems like it happened on the same day of the month — the 23rd — on which the long-ago missed payment had been due. F8 gained 37 points. Mortgage score gained 21 points. Equifax The 30D vanished completely on the first day of month 81. F8 gained 34 points. Mortgage score gained 17 points. Hooray! I’m now squeaky clean!