Answer
Check the Build Place's _projection_changes.log file for that update — it records which projections were changed, renamed, or removed in that specific release, and is the most direct way to confirm a projection is genuinely gone rather than just renamed. Because a release that introduces a significant restructuring (like 23R1's move to entity projections) can produce a long list of changes with no obvious 1:1 renaming, comparing the actual projection calls in the debug console for the same business flow across both versions is a reliable fallback way to identify the replacement projection when the changes log alone doesn't make it clear.