same as old version, e.g. 1.15.2
If the iron golem gets no cracks, then the glowing effect looks fine. After cracking twice, the outline of the glowing effect returns to normal.
[media]
(version 1.16.1)
I does not have this issues when I was playing the server with version 1.14.2.
Since I updated the server to 1.14.3, most of the villagers do flash the trading pages.
And when I wanted to try downgrade the server version back to 1.14.2, about 98% of villagers disappeared. (Same world. I have saved the world before stopping it. Loading back the copy, villagers are still there.)
Does it happen in a server? If yes, I think you should check the speed of the network. If it is low, the server should kick you out with "Timed out". Also, all the items and structures will remain the same as you first logged in.
Same here for older version, e.g. 1.15.2. Maybe the problem from the login mechanism