I have listed several serious Baptist theologians who truly reject the Penal Substitution Theory of Atonement.
Several were Mennonite theologians (which are Baptist) but a few were Baptist pastors.
I am a member of a SBC congregation. Within the SBC there have been several pastors objecting to the Penal Substitution Theory of Atonement. It is not a "hot topic" but enough of a topic for the SBC to write a resolution advocating the Theory. The resolution has been challenged.
This is interesting because the SBC confessional statements have historically been written to accommodate both penal substitution and non-penal substitution Baptists.
Here is part of an article from The Evangelical Theological Society:
Since its founding, the Southern Baptist Convention has deliberately permitted a variety of substitutionary theories of atonement. Apparently unaware of this fact, in 2017, messengers to the annual meeting passed a non-binding resolution on the necessity of penal substitutionary atonement.My Account Status | The Evangelical Theological Society
W.T. Conner was a Baptist theologian rejected Penal Substitution.
James Garrett was (Distinguished Professor Emeritus of Theology at Southwestern Seminary and a leading theologian among Southern Baptists) rejected the Penal Substitution Theory of Atonement.
I mentioned Greg Boyd (Yale Divinity School, Princeton Theological Seminary). He is Baptist and rejects the Penal Substitution Theory of Atonement.
Matthew Emerson is a Southern Baptist theologian who rejects penal substitution.
Lucas Stamps is a Baptist professor who rejects the Penal Substitution Theory of Atonement.
Graham Walker is a Baptist theologian and professor of theology who rejects penal substitution.
Steve Chalke is a Baptist minister and writer who rejects the Penal Substitution Theory of Atonement.
Mark Baker is a theologian and missionary who rejects Penal Substitution Theory.
That's a quick, short list. If you want more just open your eyes.
But most Baptist theologians hold the theory (or some form of it) as best explaining the cross. Baptists are a mix of Reformed and Baptistic doctrines.
There are Reformed churches who reject the Penal Substitution Theory of Atonement as well, so there should be no surprise there are Baptist theologians who view it as an error.