When importing, the check box "Into Subfolder" is checked and a folder named, but if you don't click the checkbox to uncheck it and then re-check it, it doesn't import into the subfolder even though it looks like it is going to. This happens to me multiple times a week as I am importing multiple projects everyday. Inevitablly several hundred photos randomly end up in the root folder during various imports throughout the week.
What version of LrC and MacOS? In the area below the designated subfolder, you need to have a specific folder selected. In your screen shot, those all look closed.
Here is what I'm talking about.
I just conducted this procedure, twice on my 2021 MBP M1 Max Max, LrC 11.3.1. I did not have your issue in the initial and subsequent second import all the images went into the designated folder.
PS - The screen grab is from my LrC 11.2 on Win 10 just for demonstration purposes.
Yes the main folder is clicked... the checkbox is clicked for Subfolder, but randomly puts everything into the root folder. It usually happens when doing multiple imports into different subfolders. With each subsequent import the checkbox shows it's checked and if you just change the subfolder name but don't physically uncheck and re-check the Into Subfolder box, it dumps everything into the root folder selected. Just happened to 3 project I was importing. I was careful on the first import, select my root folder check the subfolder box, tpye new name of subfolder and import. Imported a 2nd, 3rd and 4th set, renaming the subfolder each time and checkbox still there, but I didn't physically uncheck and re-check the Into subfolder box and those 3 imports all dumped into the root folder instead of the 3 subfolders. Incredibly frustrating, aggravating and a collosal time suck. I imports thousands of images a day. I'm always on the latest version of LRC and this has happened on my 2019 imac and my latest M1 MBP. It is absolutely a bug and I have replicated it many times, but it's not every time. The bug is the check box showing on for "Into Subfolder" when it in fact is not on. I now have to go clean up this mess from today. Brutal Adobe... brutal.
Mac OS 12.3.1 / LRC 11.3.1
Before rolling back, you might try resetting LR's preferences:
LR sometimes soils its preferences file, and resetting it can fix all sorts of wonky behavior like this. That article explains how to restore the old preferences if resetting doesn't help.