Right now (12/09/20) Britain is out of the EU but adhering to EU food standards. When the transition period ends, Britain can lower food standards to keep British food cheap. That could be allowing more filler in sausages and relaxing pig welfare standards.
The European Union is rightly proud of the highest food standards in the world and it will not allow inferior food to be imported. If British sausages are made from pigs reared in awful conditions and/or with filler content exceeding the EU standard, then the EU is entitled to reject them. Just as British standards, now and in the future, could reject food from other countries, as not meeting the British standard. In 2019, 60% of UK food and drink exports went to to the UK and was worth £5 billion to the British economy.
The food standards don’t just cover edible products, they also cover things like infections on farms and in processing plants. In 2001, foot and mouth caused a £3bn loss to farmers. The actual cause wasn’t found, but it is suspected that it came from untreated catering waste, fed to animals on a farm in Northumberland.
In 1986 BSE (bovine spongiform encephalopothy) , colloquially known as ‘mad cow disease’ was found and by 2014, 177 people had died of the human variant. The last known case of BSE was found in Aberdeenshire, in October 2018. BSE has also been found in France, Canada and in the USA, since the Nineties.
Currently (13/09/20) Germany is dealing with African Swine Fever in wild boars.
Food health matters.