As sibling comments say, this is a common feature of learning to write that doesn't indicate dyslexia.
One of my relations wrote completely mirrored for a time, that was interesting. It did make me wonder if their brain was flipping the entire World; they've corrected it now. It reminded me of, da Vinci, who I think write in mirror writing for himself but used regular writing when writing for others.
Up to a certain age, the S/b/d/p/q issue is considered normal. I certainly did it through early elementary school, and since I have ADHD, I've been screened for dyslexia enough times to be fairly confident I don't have it. All 4 of my kids still did this at the end of first grade, with only one to go on to be diagnosed with dyslexia.
I think flipping and mirroring letters is just using our ability to see that the shapes are the same. You have to do some unlearning in a way, or rather recognizing that rotating a shape changes its meaning.
If you go back and look at early examples of my handwriting, every "S" was backwards, my b and d were often flipped the wrong way, as were my p and q.
My spelling was atrocious, but my vocabulary was way above average.
I also had the issue with transposing numbers while doing math.
It wasn't until I reached High School that I had a teacher who recognized dyslexia when he saw it.