I agree that the resolving Search for Blex  ^Flip will do nothing. I am, however; confused by the assertation that the spell will go to the graveyard. Reezug, the Bonecobbler doesn't say "in addition to its other types" and so the Search for Blex  ^Flip will no longer be a sorcery. The bit about "Instant and sorcery cards can’t enter the battlefield" in 110.4 and 712.13a will not apply since it is not an instant or sorcery.

plainsrunner: Teferi's Protection gives "protection from everything" as well as stating that your life total can't change. You need something to stop the damage prevention from the protection keyword. Even after stopping damage prevention the Teferi's Protection player's life total can't change. But damage will be done and will play out as you explained above.

That is correct.

There was nothing in particular that happened in 2019/2020 that "made" 3.58 "too high". I would even suggest that it is a personal experience thing, since I feel that 3.58 is high to the point of needing to come down a bit starting around 2016/2017. It all comes down to playgroup and the experience you want.

I started playing commander in 2013 and my first 3 decks all had an average CMC over 4 and I thought anything up to 4.25 was fine. As my group got more refined average CMCs that high started becoming a problem. So around 2015 I started aiming for the average CMC to be under 3.75. Another couple of years and I started wanting to run sub 3.5. From there I started to tuned to different play experiences since pushing the average CMC any lower started to break other people's expectations for the game.

Now I run decks with average CMCs of 1.89-3.94 with the sole deck over 3.5 being a Miirym deck that isn't supposed to win; the decks below 2.75 tuned to a competitive experience; and the casual decks being 3.0-3.5. So it is my take that anything over 3.5 is too costly even in the most casual environs and has been for nearly 10 years. As always though, YMMV and if you are in a playgroup where you can run that slowly, then there is nothing wrong with a higher CMC.