Installed python3 before it was made the native python on the dist. Half broke everything, including apt & python. So I uninstalled it, and then everything was broken. Finally got python3 reinstalled, and lived with it kindof working & awful distribution updates.
I have finally freed myself of that prison last month, by nuking everything and starting fresh.
I’ll happily say I must have overlooked something, but I did try using update-alternatives. I don’t remember all the nuts and bolts from the start, but it involves python3 and distribution upgrades. I spent a good number of nights over the years trying to unmess it up, and am happy to never think about it ever again.