I haven't had this issue in a while, but checking the file history of greetd/sway-config I realized the fix was never actually added there. I must have added this fix to all my machines locally and forgot about it. I'm going to submit a PR with a fix for this.
I just updated to 0.15 in a VM and I encountered what I thought was a regression: greetd now takes the infamous 20-30 seconds to move past a solid grey screen (https://github.com/swaywm/sway/wiki#gtk-applications-take-20-seconds-to-start).
I haven't had this issue in a while, but checking the file history of
greetd/sway-config
I realized the fix was never actually added there. I must have added this fix to all my machines locally and forgot about it. I'm going to submit a PR with a fix for this.