Are the VDB update tied to the Snort Rule Update

[hurricane05]

Each year during holidays, management has deployment of signature updates (VDB & VRT) in our Firepower setup on hold (Change Freeze) due to limited team members on hand in case of issues. We recently deployed VDB update 350 to the FMC but then noticed it didn't need to be updated to all our managed FTD devices which was very strange so we didn't bother pushing VDB 351.

So our question is, is the VDB tied to which VRT is installed on the FTD devices and since our VRT hasn't been updated recently is that why VDB isn't being updated on the FTD? For instance, the current Snort rule installed on FTDs is 2021-12-15-001-vrt and VDB is version 349 even though the FMC was updated to VDB 350. We are running FMC & FTD at 6.7 version.

Thx in advance for any assistance provided.