I did an eSIM transfer to my new phone but a lot of things are missing like my apps, background, favorites and some contacts on my new phone. Is there a reason for this?

iPhones do not store any data on SIM or eSIM. So transferring eSIM or SIM will not affect the device data.

For example Contacts:

Unlike some Android devices, contacts are neither stored locally on an iPhone nor in SIM. They are synced to an email account that you had Google, iCloud, AOL, Exchange, Outlook, Yahoo or any Other

If you have a corporate email account added through a profile on your device, please check with your organization's system administrator.

Transfer eSIM does not transfer your iPhone data to another device. In order to have your background and other data transfer you need to do a backup and restore the back to the new iPhone.