Downgrade shingles to cover other roof fixes

My roofer is currently working with the adjuster on a hail damage claim. The shingles that are damaged are high dollar dimensional shingles. He has suggested to me to downgrade the shingle one step and use the freed money to fix ventilation problems (of course ventilation fixes would not be part of the claim.) He says he does not need to get the adjusters approval for the ventilation fixes, only a total dollar amount for the claim and it can be spent anyway I chose. Once the work is complete, the invoices just go to the insurance company for payment. The invoices will not exceed the approved amount and may actually be less.
Is this a common practice? Would the insurance company approve payment of the invoices? Any expericence?

How is he correcting the ventilation?
Is he correcting the “intake”(the soffits)?
Or just adding out-take ventilation at the peak?.

Adding out-take ventilation at the peak is minuscule in cost and should be included in most roof-replacements.

The prior roof job converted from roof vents to soffit and ridge vents. In the vaulted ceiling area the previous roofer did not put baffles in so air flow is negligible due the insulation. The current roofer will have to remove some of the sheathing and put the baffles in and then replace with new sheathing.