Implications of Enh #2969 (Optimize check for unchanged files during backup)

Many thanks for the release of restic 0.11.0, support for VSS sounds promising!

Here I have a question about Enh #2969 (Optimize check for unchanged files during backup)

Formerly the strategy was:
“The archiver module performs an extra fopen check to increase the probability that the file information has not changed from the previous stat.”

I unserstand, now this fopen check is skipped.
What are the implications of this enhancement (beyond improving speed)? To me it sounds like there are scenarios where the additional fopen gives more accurate backup results. What are those scenarios? (the former fopen check was implemented for)

Just changes that happen during the current backup run?
Or does(did) using fopen also improve the accuracy of detecting changes that happened since the creation of a former snapshot? (before the current backup was started)