Follow-up question to Why do most scientists think Brexit is bad for British science?
If Brexit is bad for British science, then naively one would expect that the rankings of British universities should worsen after Brexit. This doesn't seem to have happened. Among the three most widely-followed rankings and comparing to the 2016 results (which is when the Brexit referendum happened):
In the QS rankings, Oxford improved (#6 to #2), Cambridge did not budge, Imperial & UCL switched places with one another, Edinburgh improved (#21 to #16), Manchester improved (#33 to #27), KCL dropped (#19 to #35), LSE dropped (#35 to #49)
In the THE rankings, Oxford did not budge (it couldn't improve either, since it is ranked #1), Cambridge dropped by 1 place, Imperial dropped by 4 places, and UCL dropped by 3 places.
In the ARWU, Oxford did not budge, Cambridge improved by 1 place, UCL did not budge, Imperial dropped by 3 places, Manchester did not budge, Edinburgh dropped by 3 places, and KCL improved by 3 places.
Overall it doesn't look like much has changed. Some universities certainly moved a lot, but not the UK's universities as a whole.
Why hasn't the rankings of British universities dropped? I can think of many possible reasons, e.g. the effect is delayed, the rankings are not reflective of the situation on the ground, the British government provided the political support to have Brexit without British science suffering (per avid's answer to linked question), etc., and I am wondering which explanation(s) are correct.