The sponsor needs to continue to meet income requirement until the application has been approved. That's why many people ask their spouse to be cosigner just in case one person lost he/her job, the spouse can still help to meet the income requirement.
This is an older guide from 2022 spnsorship. I don't think the 2023 one will change a lot regarding to meeting income requirement.
https://www.canada.ca/en/immigration-refugees-citizenship/services/application/application-forms-guides/guide-5772-application-sponsor-parents-grandparents.html
Do I (the sponsor) have to continue to meet the income requirements during the processing of the application?
If new information indicates that you may no longer meet the income requirements, your income may be reassessed at any time during processing. Your income could also be reassessed if more than 12 months have passed between the dates since we received your application and when processing of the application begins.
You and your co-signer, if applicable, must meet the amounts outlined in the Income for Parents and Grandparents Sponsorship from the date on which IRCC receives your sponsorship application until the day your family members become permanent residents of Canada.