The problem is not the barrack's effect. Early units (built without them) will have gained XP and some promotions. Later units (built with barracks) will be able to catch up to this level faster. Deleting the older, already promoted units seems unnecessary, imo.
The issue I have is - as usual in CIV6 - related to the UI:
There is no way to tell, which units enjoy the effect of barrack-increased XP gain.
As there is no clear notification (unless the combat-preview is active), which units gained the "Spear of Fionn" effect, which one climbed Mount Everest and so on and so forth. How are we supposed to keep track on these benefits? (Please, don't suggest to rename each and every unit that visited such locations ... this would be cumbersome to no end!)
The issue I have is - as usual in CIV6 - related to the UI:
There is no way to tell, which units enjoy the effect of barrack-increased XP gain.
As there is no clear notification (unless the combat-preview is active), which units gained the "Spear of Fionn" effect, which one climbed Mount Everest and so on and so forth. How are we supposed to keep track on these benefits? (Please, don't suggest to rename each and every unit that visited such locations ... this would be cumbersome to no end!)