There was an option at the end of the test to get results by email of download a copy.
Looks like this.  Atleast proves that you appeared.
Here is what it looks like.
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This is an automated message. Please do not respond to this message. 
Application number: [REMOVED]
Dear Applicant,
Thank you for completing the test!
Your score was 18 out of 20
You need to answer at least 
15 out of 20 questions correctly to pass.
Your questions were about the study guide:
Citizenship test based on Discover Canada
Date of the test: April 9, 2023
Time completed: 10:53 PM MDT
This score is
- temporary
 
- not your official test result
 
If we suspect or know you have cheated
- we may decide your test is invalid
 
- an Immigration, Refugees and Citizenship Canada (IRCC) official will follow up with you
 
In the upcoming months, we will
- review and confirm your official test result
 
- contact you with next steps
 
This is an automated message. Please do not respond to this message. 
If you provided your email address on your application form, you authorized Immigration, Refugees and Citizenship Canada (IRCC) to send your correspondence and personal information to this email address.
- Please check your email regularly.
 
- Check the junk mail or spam folder in case important emails get filtered.
 
- Any emails we send will end in "@cic.gc.ca" or "@international.gc.ca." (please add them to your “safe senders” list in your email account).
 
- If we receive a reply that this email address is not functional or no longer exists, we’ll send a letter to the address you provided or call you at the number provided on your application form.