PlatformIO has a “find actual library sub-folder” logic as seen in PlatformIO downloads subfolder. Recently some improvements have been done in Library without includeDir unpredictable · Issue #3887 · platformio/platformio-core · GitHub, but it seems the behavior is still not perfect, especially when the behavior is different for Windows + Linux.
Open a CLI and execute pio upgrade --dev, then delete the old downloaded library again and have PlatformIO redownload it. Is the behavior still the same? → Please open a new bug report in Issues · platformio/platformio-core · GitHub.
You can fix it the same way as described in the referenced topics though as a hotifx. Fork + add library.json in the root directory.