Thanks for the quick response! Looks like the problem is solved!

Regards,
Steven

Thank you very much!

Regards,
Steven

now there would be a problem with working_days not updating when it gets a new value, what could be the problem?

Working_days compute field method:
@api.multi
def _compute_working_days(self):
for record in self:
record.working_days = sum(record.holidays_ids.mapped('working_days'))

@api.multi
@api.depends('holidays_ids')
def _compute_working_days(self):
for record in self:
record.working_days = sum(record.holidays_ids.mapped('working_days'))

Try this hope this will work

I try this, but it's not working.
Here are all the fields:

yearly_pool = fields.Integer(string='Yearly pool')
working_days = fields.Integer(string='Wordkdays count', compute='_compute_working_days', store=True)
remaining = fields.Integer(string='Remaining', compute='_compute_remaining', store=True)
holidays_ids = fields.Many2many('hr.holidays', string='Freedoms allowed ', compute='_compute_holidays_ids')

Field methods:

remaining:

@api.multi
@api.depends('yearly_pool', 'working_days')
def _compute_remaining(self):
for record in self:
record.remaining = record.yearly_pool - record.working_days

working_days:

@api.multi
@api.depends('holidays_ids')
def _compute_working_days(self):
for record in self:
record.working_days = sum(record.holidays_ids.mapped('working_days'))

holiday_ids:

@api.multi
def _compute_holidays_ids(self):
for record in self:
record.holidays_ids = self.env['hr.holidays'].search([
('employee_id', '=', record.employee_id.id),
('year', '=', record.year),
('state', '=', 'validate'),
])