I lost progress with Flamey in the 1.8.0/1.8.1 update (Cozy Grove)

Don't worry, you did not lose progress. In version 1.8.0 we adjusted both the numbers of Spirit Wood (a.k.a., Spirit Logs) required for each Fire Level (a.k.a., Scout Level) and the rate at which you receive logs. There are more logs required in some situations, but you also will receive logs more quickly than you would have in previous versions. According to the game's designers, it ultimately balances out.

The reason your "current logs" seem to have decreased is that the game actually tracks the total number of logs you've ever fed Flamey, not the amount acquired toward the next level. You gain new Spirit Scout levels as that total passes various milestones, and "current logs" is the amount you've gone beyond the last milestone. After the 1.8.0 re-balance the total you've collected hasn't decreased, but since the update moved the milestones your total isn't as much beyond the last milestone as it used to be.