Things to note here :
1 - Australia removed because we don't have a marker on Max. Monaco removed because it's a procession with no real indication of true pace. Canada is removed for Ferrari since it's not representative data.
2 - Gap between Ferrari, McLaren and Mercedes remains relatively stable throughout and the jumps are easily explainable. Mercedes basically admits they are struggling with the car after Saudi (car did not work on high-speed). They start to recover at Imola (and actually take another step in Monaco with the new front wing is quali gaps are to be taken into consideration). Mercedes is generally flattered by low-temp races, hence the "wavy" form in later races.
Ferrari hits trouble with porpoising after the Spain upgrade. They fix it somewhat in Hungary and Italy brings an even bigger improvement. Note that Ferrari is an outlier in Italy because they were the only one to 1-stop, whereas the gap between Merc, McLaren and RedBull is representative as they all 2-stopped.
3 - The only thing that sticks out like a sore thumb here is the MASSIVE chasm in performance deficit that is instantly overcome by all teams that are directly following RedBull after Miami. McLaren overturns a 0.2% deficit to Ferrari to a 0.2% advantage with their huge upgrade, but what is interesting is that Ferrari, without bringing any sort of upgrade also completely cut the gap to RedBull at Miami. Even Mercedes, which at this point was still struggling with their car, manage to get their best performance of the season relative to RedBull.