You are confusing taste and quality....
If there is no objectivity....then you would have no basis to explain why a film is better or worse than another, A student first iPhone short would be equal to The Godfather. A child banging pots would be indistinguishable from a Symphony.
The moment you say something is good or bad, we can talk about craft, skill, storytelling structure and emotional impact, all of which can be measured and compared and where this movie fails on all parameters...
You can personally dislike something excellent...for example few people can appreciate the genius of Miles Davis, and enjoy something mediocre... Too many to quote here...but Project Hail Mary is one :-)