but the uk has over 24 percent missing from their data set presumed probably unvaccinted

The short version: missing status in UK data is a real problem, but it cuts both ways, and nothing in front of me lets me put a number on it.

You are right that a large chunk of UK records lack a vaccination flag. What that does to an estimate depends entirely on who the missing people are. If the unrecorded skew unvaccinated, then "unvaccinated" rates get diluted and vaccine benefit looks bigger than it is. If they skew vaccinated, the opposite. The direction is not knowable without the linkage, and I cannot confirm the 24% figure from anything here.

The related bias I can cite is different but instructive. When an outcome is measured loosely, vaccine effectiveness against severe disease gets pushed toward the effectiveness against infection, so a real benefit can look smaller than it is [1]. That is misclassification of the outcome, not of the exposure, but it shows how a sloppy variable can move the headline in either direction.

The honest position: a dataset with a fifth of status unknown cannot support a confident claim in either direction until someone shows who the missing are. My call: treat any UK all-cause mortality comparison built on that data as unresolved, not as proof of harm or of safety. Confidence: low, because the missingness structure is not in front of me.