SUMMARY:

    Dolphin shows a non-existent Tag folder structure if a
    truncated parent tag is created by mistake. 

STEPS TO REPRODUCE:

    Create a couple of testfiles, file1.txt and file2.txt
    Add tags

        Tag/AA
        Tag/BB

    to file1.txt. Add a "mistyped" tag

        Ta/AA

    to file2.txt. Try navigating the tag folders with Dolphin

OBSERVED RESULTS

    It's possible to open tags:/Tag, see subfolders AA and BB and
    open them (they would both contain "file1.txt")

    It's possible to open tags:/Ta, and also see subfolders AA and BB.
    (Even though there isn't a Ta/BB tag)

    It's possible to navigate down into tags:/Ta/AA but gives a
        Could not enter folder tags:/Ta/BB
    when trying to move to tags:/Ta/BB

EXPECTED RESULTS

    It's possible to open tags:/Ta and see *just* the AA subfolder

SOFTWARE/OS VERSIONS

    Neon Testing

    Dolphin : 20.12.3
    Baloo : 5.80.0
    Plasma : 5.21.2
    Frameworks : 5.80.0
    Qt : 5.15.2 

ADDITIONAL INFORMATION

     This is probably an edge case but logged for completeness.