W - I'd believe your assertions more if whenever I checked them they proved correct.
The process to generate a flu vaccine is normed . Always known, old tested virus are used. Nothing new at all. Further always at least 3 strains are mixed not a single. May be you did look in a teaching textbook...Of course they can use the HxNy of the last season for a new vaccine as the difference from season to season is minimal and the process is always the same.
A new vaccine is either based on a completely new technology or a new illness new strain of virus or a new carrier virus or a new method to immobilize the carrier. Even new adjuvant should be treated the same as new vaccines see Pandermix (swine flu) case.
So none of the above is the case for flu vaccines. Always the same method same process since 50 years that's why these "your believed new vaccines" only need basic tests.
The problem of CoV-19 vaccines is that all of the above is new except the carrier virus in vector vaccines. Nobody has 40 years experience how changes in the CoV-19 virus affect a "new" vaccine. The Pfizer vaccine is deadly crap and if you change untested crap it will remain untested crap.
Just yesterday, CNBC reported people in the US have still died or been hospitalized from COVID-19, despite being fully vaccinated. CNBC also reported that 76% of hospitalizations from breakthrough cases occur in individuals over 65.
We need more data about age and vaccine failure!!