I haven't yet had a chance to populate one of my boards and test things. Naturally, I am supremely confident that it will work first time. But if I did, hypothetically, need to make more PCBs, here are a couple of things that I would change. None of these are fatal.

• In the KiCad footprint for the ESP32 module I am using, the antenna circuitry is off the end of the main board. I placed it on the PCB so it would hang over the edge. The idea is to reduce any degradation of radio signals from proximity to other components. I can't believe I didn't notice this earlier, but the actual antenna placement is between the last couple of pin headers on that end of the module. In my PCB layout, there is part of the bottom layer copper pour under the antenna. I would revise that to avoid copper directly under the antenna.
• The 12v power connector footprint is an excellent fit for the connectors that I have on hand and plan to use. I thought that it was also a good fit for some less expensive connectors (which I also have on hand) made by the same company, but it's only close and not a good match-up. I would rework that so that both of those connectors fit easily, and I might put in some additional power connector footprints so that dime-a-dozen unbranded power connectors could be used more readily. However, even without using the exact part that I selected, someone could use the kind of power connector that attaches to the PCB with wires and is then secured to the enclosure with a nut or something. I'd lay down some more obvious "+" and "-" markers on the silk screen for that possibility.
• I used right-angle horizontal footprints for the I2C JST SH and PH connectors. Those connectors come in horizontal and vertical entry formats. Since I laid out two of each footprint, I would probably change that to one horizontal and one vertical footprint for each. Too late, I discovered in my accumulating parts bucket that I had vertical connectors for both. For the JST PH connectors, it's a simple matter to use the same footprint as long as you are careful with the orientation. With the JST SH surface mount connectors, it's not really a good match-up.
• The footprint I choose for the electrolytic capacitors was a bit arbitrary, except for being radial. Hobbyists buying a few capacitors won't always have a good selection of lead spacing. I would probably lay down some additional lands for one of the leads to more easily accommodate different spacing. With a radial capacity, you can make almost anything work by bending leads. It just won't be as tidy looking as a straight-in exact fit.
• I would make the mounting holes a little bigger. They look nice and big when I'm looking at the layout in KiCad, but on the real boards they are smaller than my mental image of them. (They were manufactured exactly as I designed them. It's not a manufacturing flaw.)
• There are a couple of jumpers for some optional features. The jumpers have to be set in pairs to either "A" or "B". I laid out the 3-pin headers side by side, so it would be easy to think it was 3 pairs of 2-pin jumpers instead of 2 sets of 3-pin jumpers. I would offset them from each other a little bit so that the orientation would be obvious, and you wouldn't connect the wrong things with a jumper since it wouldn't fit.
• The placement of the connector for Fan 4 is slightly off compared to the placement of the other fans, for both the X delta and the Y absolute position. It's only a fraction of a millimeter, but it's annoying.
• Mounting hole Ref2 has some strange offset in the drill hole in the footprint report. I can't see where that comes from, but I'd try to track it down and zero it out. The other mounting holes don't have it, and the location of the overall center point is correct.
• The biggest change, which is a minor blunder, is that I somehow selected the wrong footprint for the MOSFETs. I didn't realize it until I finally went to place one on the PCB. I intended to use a TO-220 package. In some way that I can't recall, I selected TO-3P, which has a much wider lead spacing (0.215 inches). I'm able to bend the leads and fit the STP16NF06L MOSFETs, but it's inelegant.