I am going to be SO annoyed if any of the major-products I have ever bought end up becoming a different or more basic-level model of itself; this already happened to me some time around I think maybe around the year 2018CE or circa that time-frame where my Electrolux vacuum-cleaner, even though the ORIGINAL-Version of my Vacuum-Cleaner actually had a Floor-Vacuuming Accessory where I could plug into the end of the Wand and it had a Light on said Floor-Vacuuming Attachment, the current-version of my Vacuum-Cleaner, apparently, does NOT have that accessory anywhere; I was used to vacuuming my place even with the lights off, but, was able to see what I was cleaning because of the Light that was on the Vacuum-Attachment; it doesn't exist in what-ever the hell happened to result in the current time-world-configuration and I looked absolutely everywhere in my apartment-unit for it for a long time until I was finally forced to conclude that the damn Mandela-Effect even altered my own past-purchases. Anyway, thanks for the warning, and, for good measure, I am going to have to look around for books or papers that I had purchased that I had kept around since from over 20 years ago to write upon just in case any of the more-recent purchases are affected by any time-distortions, how-ever, I do need to ask you to clarify this 20-year-increments reference...
Namely because a lot of the Mandela-Effect Changes had affected history from as far back as the 1960s (and possibly before), such as the number-of-people in the Car that chauffeured JFK, from my Origin-Time-Line the Star-Wars Movie was also originally released circa the 1970CEs, etc., all of which didn't seem to start being noticed as Time-Alterations to Reality by too many until Circa 2015CE, even though the actual term wasn't apparently «coined» until circa 2009CE, when first noticed by a Fiona Broome (or at least the first to bring significant-attention to said phenomenon), Kit-Kat (with the dash/hyphen) also existed when I was little, amongst many other such more-than-20-year-increment changes (like that «passage» in the «bible» from Isaiah 11:6 and also numerous other writings even though the origin-publication-times/years for said «bibles» were definitely from more than 50 years ago; I have challenged anybody who grew up with the bible & remembers the passage as LION, who were «skeptical» and thought that it must just be some different «version» or «alternate-translation» or other such things that are common-rejections or excuses for those who think that time-travel is impossible or that history cannot be changed/altered or such things of that nature to find ANY version of ANY bible where the word «Lion» still exists within... obviously they cannot).
Why would history from as far back as the 1960s have changed some time between possibly some time circa 2009CE to 2015CE (and quite possibly/probably to the present) also be changed/altered if the «time-reset/civilisation-reset» attempts occur only in 20-year-increments ? I am interpreting the «20-year-increments» description as being where they can only change as far back as 20 years or did you mean their attempts have historically been in 20-year-increments ? How far back can they affect ? Certainly, affecting as far back as the «Big Bang» requiring far more amounts of energy that can be pulled off than is currently available certainly makes sense if this «Law of Conservation-of-Energy» is applied to the Quantum-Levels, and, whilst I have considered that «parallel-worlds» may be «merging» into a combined reality (maybe some parts of the current existence-configuration(s) are), even that is insufficient for me as I would think there may be some kind of over-laps where both worlds are seen simultaneously (but maybe not necessarily since there are factually phenomena where sound cancels each other out, sounds being a frequency, and, because all of existence are configurations of frequencies, perhaps the more-dominant-world would cancel out the less-dominant-world or at least most or much of it or even something related to the vibrational-level of the collective-spiritual-consciousness affecting the results as to which world becomes dominant... obviously this would show that collective-consciousness is on the decline if the latter is the case, but, then again it was also written by Terence that there is a great out-pouring of the Light-Energy which is «exposing the darkness» everywhere to the point where it will no longer be possible for anybody to hide from their karmic-pasts... even the ones whose names we never hear and faces we never see), but, damn I hope I am not digressing too much... anyway... thanks for the warning. I will take measures...
Related & interesting presentation...
https://odysee.com/@alanthier001:7/Glitches-In-The-Matrix---Complete-Edition:4