Max villagers despawn

Hello
since 1.16.0.66 the villagers disappear as if nothing had happened
I even lock them in a house with iron doors and they have despawn
I am surviving on most of my parts so you understand that the villagers are often essential to me more the first to disappear are all the time the ones that I have increased to the maximum level and as they disappear this therefore leads to the loss of all resource that I have glued to make them evolve this is very frustrating do your best to correct this bug please