I find these brown bumps and spots on many different genera of succulents.
I always thought it was a fungus. Was told at one time by U of H Ag extension testing service that it was Crassula Brown Spot Fungus. Since there is no such thing I felt they were appeasing me and did not know what they were talking about.
When you pay for testing they "have to tell you something".
Now I know different since I read this article in Greenhouse magazine.

Jan Byrne, "The Michigan State researcher discusses powdery mildew on succulents, a topic she recently wrote about in an e-Gro alert published with Roberto Lopez and Mary Hausbeck.
On succulents, powdery mildew does not spore readily. So you don't always see that white powdery look — what we think of typical powdery mildew symptoms. Instead, you see this kind of corky scarring or scabby-like lesions that are produced on the surface of the leaf."


Fortunately I do not have this issue right now but I am very familiar with it.
So I had to borrow a photo from the internet to show the symptoms.
The credit for the photo goes to Pinrest.
The bump on the center leaf is what I have seen on my plants for many years.
I have seen other people on this forum asking about these same spots.

I think I got rid of it by spraying many different fungicides over the years, or maybe
I got rid if it with Baking Soda. I treat my catchment, rain water with baking soda since it is acidic.
I use the baking soda to raise the pH.
Hope this helps some of you.

I have seen brown spots on a few plants in this family and concluded they were disease-related (virus, fungus, etc.) without necessarily knowing what the exact problem might be. My solution typically involves culling the affected plant if it's not the only one I have, assuming that the problem may be contagious. When I have left plants alone, the problem seemed progressive (slowly taking over all the leaves) and did not spontaneously resolve. When I have subtracted affected plants from the patio, the remaining individuals of the same cultivar or whatever avoided any apparent infection. So I guess culling the herd works to keep it strong.

I did recently have a powdery mildew problem with 2 Euphorbias, and I treated it with a fungicide spray (Ortho product), but I suspect the solution will require repeat visits. Fungal issues like that white mildew and a similar black version tend to pop up at this time of year when we have lots of fog accompanying our usual high (80%) humidity.