The vaccines are quite clearly getting progressively more leaky as T cell durability is good and antibody durability is poor.  The effects of leaky vaccines on viral evolution are bad: if infection is not prevented but the most serious symptoms are, then more pathogenic strains can have their hosts survive long enough that they are transmitted onward.  This can result in very lethal pathogens.  The most famous example of vaccination apparently causing this is in Marek's disease, as exhaustively demonstrated in a 2015 paper.

epidemics.psu.edu/.../leaky-vaccines-promote-the-transmission-of-more-virulent-virus

I don't want to see the same thing happening here, but it looks like it may be, as recent mutations have been largely focused on S2 and ORF1ab, which would presumably increase viral load.

There is no further effort to modify epitopes in the RBD or change binding affinity.  E484K and N501Y have totally failed in AY.*.