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Here is my timeline:

Invitation email: 2025-07-30
Submitted Application: 2025-10-07
Payment: 2025-10-07
Additional Info Required email: 2025-12-01
Submitted Additional Info: 2025-12-08

So far I have not received an AOR or any additional email. Should I be concerned?

Only site I've been looking at is the Permanent Resident Portal and status is 'Submitted': https://prson-srpel.apps.cic.gc.ca/en/login
 
I got that letter but no mention of CSQ at all. But is this usually mentioned in the same letter?
I received a separate request letter from IRCC asking for the CSQ + other additional documents.

However, my sponsor eligibility letter did state the following:

Provincial Requirements for Residents of Quebec

If you are a resident of the province of Québec, you must submit an undertaking application to the Provincial Government.
To download the required forms, please consult the Ministère de l’Immigration, de la Francisation et de l’Intégration (MIFI) website at www.immigrationquebec.gouv.qc.ca (Sponsors and Sponsored Persons section).
Complete the required forms and promptly submit them to the MIFI at the address provided in the provincial guide. Do not submit any of the MIFI forms to this office as they will only be returned to you. You must enclose a copy of this correspondence with your undertaking application to MIFI. If you received this communication via email, you may print a copy to be enclosed with your undertaking application to MIFI.

I think if you already received this sponsor eligibility letter you should be good to proceed with CSQ once Quebec restarts accepting undertaking applications in June.
 
I received a separate request letter from IRCC asking for the CSQ + other additional documents.

However, my sponsor eligibility letter did state the following:

Provincial Requirements for Residents of Quebec

If you are a resident of the province of Québec, you must submit an undertaking application to the Provincial Government.
To download the required forms, please consult the Ministère de l’Immigration, de la Francisation et de l’Intégration (MIFI) website at www.immigrationquebec.gouv.qc.ca (Sponsors and Sponsored Persons section).
Complete the required forms and promptly submit them to the MIFI at the address provided in the provincial guide. Do not submit any of the MIFI forms to this office as they will only be returned to you. You must enclose a copy of this correspondence with your undertaking application to MIFI. If you received this communication via email, you may print a copy to be enclosed with your undertaking application to MIFI.

I think if you already received this sponsor eligibility letter you should be good to proceed with CSQ once Quebec restarts accepting undertaking applications in June.
I contacted IRCC and they did confirm it was my AOR letter even though AOR is not mentioned on it. It's good that you got confirmation in writing that you should submit the undertaking application. No guessing there. For me it was not mentioned at all. Like you said, I will have to wait for when they restart accepting the undertaking applications. I was also advised to contact MIFI to check if ok to send the application.