Inland Sponsorship Fees 2019 vs 2020

[KR8994]

I submitted the the inland paper application to sponsor my spouse in December 2019. I paid $1125 and attached the receipt with paper application. Spouse today received an email reminder for Biometric fees payment. The amount I paid in Dec 2019 includes the Biometric fees. The Right of Permanent Residence fees I believe used to be $490 at that time which is $500 after April 30/2020. I hope they will figure out that total amont of $1125 includes the Biometric Fees As per the old fees structure ($75 sponsorship fees + $475 Principal Applicant Processing Fees + $490 right of permanent residence Fees + $85 Biometric fees). Can there be any other reason for the email reminder for fee payment?