I wouldn't be concerned with this TSB if you're a DIY'er.
This.
I did my first oil change myself, and didn't use a genuine Subaru filter. (Not recommending or disclosing what I used).
I wonder if the dealers are charging extra, or eating the cost of the added oil/labor. It's not exactly the customer's fault they are having supply chain issues. The cost of 4 additional quarts of synthetic is going to be a tough sell on that first oil change service.