Yes, if you had been tipping 20% all along
Why? food cost had gone up because of inflation. So tips should go up too. Otherwise, the waiter got money that is worth less. Keep the percentage, the amount go up with the price.
In the event you think food cost in a particular restaurant gone up more than it should, perhaps eat elsewhere?
My position is probably a bit unusual on this. If the food is below standard, I tell the server and expect a new dish made, or a discount to match the quality of the food.
On decent restaurants, servers would do that. I tip as usual if the new dish is up to standard. If it's a discount, I still tip according to the original (undiscounted) cost.
I've been in a few situation that, after I pointed out the food had problem (this could happen by mistake), I got a new dish AND a discount as an apology for the mistake. In this case, I add the discount amount on top of the usual tip. After all, I got the food I expected, I had planned to pay a certain amount. The restaurant gave me a discount to make me happy. I'm free to give that money to the server to make him/her happy.
But if the server did nothing, I lower the tip amount depending on how unsatisfied I was with the whole meal.
Waiters are the face/representative of the restaurant. They should know if they work for a shitty outfit, they'll get shitty tips.