There is a potentially a second issue that might appear.
There has been a long term (and very slippery) bug where you can search “Your Files” with Dolphin and find a match but if you go to particular folder and search from there, you don’t find the match.
You can also see this when using the command line:
$ baloosearch -i "the file you are looking for"
will find the file (which you might have in your Documents) but
$ baloosearch -i -d ~/Documents "the file you are looking for"
does not find it.
This is being tracked in: bug 474973 – baloosearch (as well as Dolphin and other apps using baloo) do not find anything when serching files inside the Downloads directory.
Previously it mostly affected BTRFS users (some assumptions are being made here) but with the Frameworks 5.111 reindexing it can also affect “vanilla” Ext4 users.
The solution is to purge and reindex as above.
(Edit: typo in bug number)