Since you applied in October 2025, the $635 fee was the correct amount at that time.
* April 30, 2024: Protected Person principal applicant fee increased from $570 to $635.
* April 30, 2026: it increased again from $635 to $660.
* Biometrics are separate: currently $85 per person, or up to $170 for a family applying together.
Even if you are exempt from a particular fee, if you paid it by mistake, IRCC can refund the amount once the exemption is applied. you normally don't need to request the refund.