This isn't really much of an issue, practically speaking. The likelihood of someone buying a subscription is different than buying a product from an ad.

For instance, while I'm highly likely to pay for a subscription to a streaming service that lets me watch videos from creators (in my case, Nebula) I'm not likely to buy any products from a sponsorship or YouTube ad. (and haven't, thus far)

My likelihood of paying for a product in an ad is entirely separate from paying for the service those ads are on, and this is commonly true for many people.

If there's an independent news outlet I want to support, I'm going to feel more inclined to pay them than I am to buy a product in an ad, just because each carries different incentives for me. I want to support the news outlet, I don't want to buy a product somewhere else.

This is anecdotal, and I understand that, but as someone else had also mentioned before, even companies like Netflix are promoting their revenue from the ad tier, and having both is a good mechanism to keep the business afloat and allow it to acquire customers who don't want to spend too much.