many2many_tags_avatar_popover

This is a sibling of the standard avatar tags widget, defined in the same file. It adds two behaviors: an autocomplete opened through a popover rather than inline, and a reversed tag order.

get tags() {
    return super.tags.reverse();
}

The descriptor spreads many2ManyTagsAvatarField, so everything the base widget supports carries over and only the component differs.

The reversal is the same override found on the kanban avatar variants across Odoo, which suggests it exists so avatars stack correctly against an overflow counter rather than as a deliberate ordering choice.

Nothing in standard Odoo used this, so the practical audience is teams who found it while reading the source and applied it to a crowded form. If that is you, the Odoo 20 upgrade removes it, and the fallback is the ordinary avatar tags widget, which looks nearly identical minus the popover.

In Odoo 19:

<field name="user_ids" widget="many2many_tags_avatar_popover"/>

The Odoo 20 equivalent, and the migration to make:

<field name="user_ids" widget="many2many_tags_avatar"/>

Removed. Diffing the file between branches, Odoo 19 registers many2many_tags_avatar, list.many2many_tags_avatar and many2many_tags_avatar_popover. Odoo 20 registers many2many_tags_avatar, list.many2many_tags_avatar and card.many2many_tags_avatar.

So the popover variant was dropped and a card variant added, as part of the wider rename in which every kanban. prefixed registration became card.. The file itself is very much alive; only this one registration went.

Migrate to many2many_tags_avatar. You lose the popover autocomplete and the reversed ordering, neither of which was configurable anyway.