Let me preface, England and Scotland are both countries in the UK. They share the same border, to outsiders they are very similar. For what it's worth England has a much higher population density than Scotland.
England lifted their facemask mandate on 27th January, Scotland did not and have in fact extended the use of them due to rising cases: https://www.bbc.co.uk/news/uk-scotland-60750364#comments
Now you'd be forgiven for thinking that must mean England have had way higher rates of covid since this period, but this is the opposite of what happened:
https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/conditionsanddiseases/articles/coronaviruscovid19latestinsights/infections
To save you clicking on the link:
The estimated percentage of the community population that had COVID-19 in the latest week was:
3.80% in England (1 in 25 people)
5.70% in Scotland (1 in 18 people)
Isn't this rather strange, as the facemask mandate in Scotland should mean their covid rates would need to at least be lower than England?
The exact same results can be observed last summer when England temporarily lifted their facemask mandate, but Scotland kept theirs. This mirrors the study of schools worldwide comparing those which had a mask mandate against those that didn't (spoiler: there was little difference, but interestingly those schools with the mandates usually had higher covid rates).
In conclusion this invaluable data proves that there is no merit or credibility to the argument that facemasks reduce the spread of covid.