We could refer to the official document which lists the attributes that are synchronized by Azure AD Connect sync.
In Exchange online
And please note that, in a Hybrid Exchange environment, the on-premises Dynamic Distribution Groups (DDGs) are not synced in Azure AD / Exchange Online (EXO) and this is by design.
Reasons for DDGs not to be synced:
The attributes used for the DDGs queries might not be synced or named the same in Azure AD, therefore the query might not work or have the same results in the cloud as they have in the local Exchange.
In the cloud we have a flat structure so we do not have Active Directory OUs, therefore some location-based queries will not work in the cloud as they are on-premises.
Here are some related links for your reference as well:
Creating AAD Connect rules to synchronize on-premises Dynamic Distribution Groups as Exchange Online Contacts
How to deal with Dynamic Distribution Groups in an Office 365 Hybrid Scenario
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