social/mail_activity_team/security/mail_activity_team_security.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo noupdate="1">

    <record id="mail_activity_rule_my_team" model="ir.rule">
        <field name="name">mail.activity: user: my team</field>
        <field name="model_id" ref="mail.model_mail_activity"/>
        <field name="domain_force">["|", ('team_id', 'in', user.activity_team_ids.ids), "&amp;", ('team_id', '=', False), ('user_id', '=', user.id)]</field>
        <field name="groups" eval="[(4, ref('base.group_user'))]"/>
        <field name="perm_create" eval="True"/>
        <field name="perm_read" eval="False"/>
        <field name="perm_write" eval="True"/>
        <field name="perm_unlink" eval="True"/>
    </record>

</odoo>