This issue exists in versions prior to 1.20.6 however most players would not know this because paper servers up until 1.20.5 did not trigger i-frames upon shield disable
OcelotOnesie - I appreciate the work you do, however the description of that bug does not match our experience. We have had despawn events without traveling to the nether, which is different from the description of that bug. So while it is slightly similar, I do feel the difference is important to note and this shouldn't be duped as that bug.
Also important to note that the nature of this bug I reported only started happening AFTER the nether update. We have never had mass despawn events of this nature before this and have played in many towns with far more entities than we've seen despawn. I believe this is a new issue. Whether or not it's the same root cause should be determined by the dev team I think.
Here's a video of it happening in my village. https://gfycat.com/tartcomposeddeinonychus
I just had this on 1.14.1. I went through a nether portal from the nether to the overworld and when I came through I couldn't use a any chests. Right clicking with a flint and steel lit the ground in-front of the chest and right clicking with a sign placed the sign on the chest. Shifting and unshifting fixed this issue. It seems to be 100% reproducible in my 3 tests. Here's a video of it occurring: https://youtu.be/mDDlBmYG_zk
I'm playing on 1.14.1 on a vanilla SMP server.
MC-268147 Breaking shield triggers invulnerability tick behavior, despite player not turning red - Jira (mojang.com)