Hi,

You can super the compute function for that qty_available field by inheriting the model and you can call a new function inside that compute function, and you can define the function inside that model so that whenever that compute function is called the new function will be automatically triggered.
Please refer to the following code:
from odoo import fields, models


class ProductTemplate(models.Model):
    _inherit = 'product.template'

    def _compute_quantities(self):
        super(ProductTemplate, self)._compute_quantities()
        self.my_function()
   
    def my_function(self):
        print("This function will calls when compute function works")

Hope it helps