It also appears to omit that a lot of skilled workers from EU countries are doing the exact same but in reverse. I always liked the Guardian, but their stories on brexit have been terrible, to the point that you can't trust them at all.
On the other hand, https://www.compas.ox.ac.uk/2019/brexit-uncertainty-motivate... shows a (smaller, and, eye-balling it, not with a break in the trend at time of Brexit) uptick in EU naturalizations in the UK, too.
Also, in terms of recruitment, very few people are now interested in coming over to the UK for engineering positions. We used to have a lot of talented candidates from EU countries (especially Portugal, Spain, France, Italy, etc.); we have not had a single applicant from these countries since the vote.