As thngs are currently it may be that Brexit has made things slightly more difficult but Covid has made that even worse. Neither you nor I know that veterinary practice, nor the person who tweeted the image, nor the circumstances that lead to that letter being distributed,, but at present it seems that all the woes of the World are being laid at the feet of Brexit. I'm surprised that the return of the Taliban hasn't been attributed to it. ( I voted remain ).