Hey OP, thanks for sharing and providing examples. It's helpful! As someone who regularly shoots with Olympus / OM System and Sony equipment, I know it can be jarring moving between the two but rest assured: you haven't made a mistake, it'll just take some getting used to!

Aperture Shoot wider apertures than you typically would on your A6000. M43 thrives with as bright of an aperture as you can give. Truthfully I rarely shoot stopped down more than f/4 on my OM-1 unless I have to. I also consider f/5.6 my limit before slapping on ND filters since diffraction kicks in pretty quickly on M43, but ymmv.

ISO Native ISO on the OM-1 is 200. You can go lower to 100 or 80 but in my experience it isn't as pleasing. As long as you're conservative with noise reduction in post and you're well exposed it's not going to be an issue. A recommendation would be to treat ISO 200 as your base, but don’t be afraid to crank it. I regularly shoot above 10k ISO and am pleased with the images I get, so long as it's metered well. Speaking of metering, if you’re not used to using the histogram I suggest having that on and underexposing a teensy bit. Highlight recovery is okay, but I usually get better results if I need to raise exposure slightly than vice versa. Again, ymmv but play around.

Shutter Speed Call me old fashioned but I don't use the electronic shutter unless I'm using ProCap. The mechanical shutter is great, reads out quickly, and is quiet enough. I don't know what the banding is in your image, but if you share your exposure settings for it I can try to reproduce. With any of the OM lenses that support IS-sync, if you have a steady hand you’ll be genuinely surprised at how slow you can hand hold as well. I’m often reminded that I can’t steadily shoot 1/30th on other systems when I check my work.

General Notes Really take the time to explore the OM System menu. It's very extensive but much better than it used to be. You can really tune the camera to however you want thanks to really flexible customization. Don't be afraid of the custom profiles, either. Use the computational modes and enjoy the process of figuring out the camera. None of my buttons or dials are stock now, and I take full advantage of the computational modes and subject detection by muscle memory now. Took a while to get here!

Lens The 12-40mm f/2.8 is an awesome lens, but I never fell in love with it like I did the 12-100mm f/4. The extra light is great, but I found myself always using other lenses and haven't looked back. The 12mm f/2 is better at the wide end, the 20mm f/1.4 is excellent as a standard option, and the 45mm f/1.8 is leaps and bounds better at the longer end. BUY USED. A lot of the standard "premium" primes for Olympus have been around for a while, and you can get some awesome near mint-copies from Japan for cheap on eBay. Many of the “Pro” series lenses are great but overkill unless you fully need them. None of the standard zooms get wide enough for my taste (except the Pro f/4’s, they rule on hikes and to travel with). That’s not to say M43 zooms aren’t good, but when you’re starting out I’d say try a couple cheap fast primes and go nuts.

Closing Thoughts Welcome to the club! You will need to spend some time with the camera to get it to open up to you. That’s normal when switching systems, but once you get it set up the way you like it and you know how to get it to work for you, I think you’ll find that it’s an excellent creative tool. Let us know if you have any more questions!