Background verification process

Need some help with Background verification in a MNC.

In my past experience:

• I got laid off on May 2020
• in July 2020 I got a job, did not like it and left early by Sept 2020
• I joined a new company on Oct 2020

In my resume , I have skipped this experience and mentioned other dates correctly. I didn't think it would be relevant!

1. Experience A - Till May 2020

2. Experience C - from Oct 2020 - ..

3. Would this be a problem for background verification?

4. Should I inform the HR about this ?