@Deepaklal-FT , thank you for posting this question on Microsoft Q&A.
Could you please check the last run of scheduled deployment, and whether it was successful?
Also, you may refer the following link to get details of security patch on both VMs (installed and pending updated) to see if there are any differences (may be due to accidental OS config change): Linux updates shown as pending and those installed vary
If the information provided above does not help, I would suggest opening a support ticket so that this can be investigated with access to all the logs. In case you face any issue while creating a support ticket, please let me know.