"Submissive" characters, aren't really any good storytelling, either as men or women. Because you're removing their agency, you are making them inherently forgettable. So, there's no reason you would remember them, even if they were there. They wouldn't have an impact on the story.

However, let's just go with feminine characters, rather than "submissive' only. Submissive isn't ever going to be useful. So when can I think of the last feminine protagonist?

Mrs. Brisby in the Secret of Nihm. She's literally a dutiful wife and mother. Thrust into a "fish out of water" adventure. She requires the help of men on her adventure, but she also demonstrates an apt way of navigating her way around the social environment that these men live in, while also still getting their help, but never actually attacking them directly.

Rather than a strong, female, protagonist. She's a strong FEMINE protagonist.

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Femi_nihm_?

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Here's a scene where she's helping a bit of an idiot man-child to help her. She still has to confront a "Force Of Nature" threat, but the moral of this confrontation shows that her generosity and kindness (or even her motherly instinct to care for a man who is a bit childish), along with her ingenuity, is what keeps everybody safe and her objective still available.

Anyways, I think media creators have lost the understanding of what strong femininity actually looks like. Partly because I don't think feminists understand what femininity is, nor do modern people understand why femininity is useful. It's the same reason modern writers think it's hard (and boring) to make heroic characters: they are so ideologically poisoned by nihilism and cynicism that they don't even believe in the concept. Similarly, femininity is seen as worthlessness and enslavement, rather than inspirational and dutiful. I don't think calling it "submission" is a good descriptor, either. Submission is only warranted with trust. You shouldn't submit to people you can't trust. A "submissive" person, is typically prey. Now, there's strong women in modern media, but they all have a kind of "Ripley" effect. The strong women become momma bears, or cunning manipulators, or "no wrath like a woman scorned" vengeance agents in a certain time of need.

But a strong feminine protagonist, that's pretty hard to find in the past 50 years.