I haven't had this problem so much in the past but now it's almost every day.
I get the stove going, let it burn pretty hot for a half hour or so to keep the creosote from building up, then gradually turn down the upper and lower dampers to hold a medium hot, steady burn.

If I crank it back up due to a chill in the place, or whatever, then turn it down again, I think I'm doing that gradually over about 5-10 minutes, the stove will belch smoke back into the house out the lower damper.

This used to happen only if it was VERY hot and I turned it all the way down because I was afraid of a fire or it was starting to glow red (steel stove, actually, here is a link: https://www.secondroundwoodstoves.com/ I have the "Elk Camp" with permanent welded on legs and a flat top)

So it's small and heats up fast. I have brick in it. 6" double wall pipe inside, triple wall outside the house.

I burn North Idaho Energy logs and have always used them (a compressed sawdust log, 8lbs per log, max of 2 logs at a time)

Any thoughts on why it is burping this winter when it didn't in the past?