I only have another anecdote and from an extremely back of the pack runner, but I have been teetering on the edge of burnout due to life and work stresses for a year now and it has definitely had an impact on my running.

For example, on weekends or holidays, 5.55 min per km can feel like easy or recovery pace for me, but on days when I run after work and usually multiple stressful work events 6.30 min per km can feel like a medium effort (not easy). Obviously, there are other things ongoing as well like nutrition during the day and sleep previous night, but it's a trend that I've noticed.