I don't think so, because a) macOS provides correct free space information, b) It explicitly says that "your backup disk is full, and I'll open up some space, so your earliest backup will be at $DATE", before actually deleting any snapshots.

Our disagreements stem from the assumption that the reported space is incorrect to begin with, but there's already "disk on space" note on every file, which provides physical size of something.

We can argue that the progress may be calculated over that number, but I still think it has its own limitations with performance.