Find something else very dissimilar from what you do. I know a lot of programmers that game when they’re done with work. Construction workers that do woodworking. Chefs that … cook. That’s not a hobby, that’s just more work.
I restore antique violins for a living. I attempted to unwind with painting wargaming minis, airplanes, and HO railroad models. I had all the equipment and skills, so it seemed like a natural fit. I left it, came back, left again. It’s enjoyable, and I’m good at it. These hobbies just seem like working but I don’t even get money. Two hobbies have stuck the longest, and provided the most chill: gardening and aquariums. It doesn’t get much different from my work life than that.
So if you’re unwinding with soldering electronics, or doing paint by numbers art.. that’s not different enough.
You can’t just “don’t bring your work life home” when you’re self employed. Especially if you work on your own property. That’s just not reality. There has to be a transition period of doing something drastic.
If you do work from home, put your hobby equipment physically between your work life and home life. Make your three segments of the day distinct and all visible from eachother. I have to walk past the garden to get in the house. I see a weed to pull, and just like that I’ve stopped thinking about work on the way home.