Hi - I posted something here yesterday which I then deleted as I managed to get past that problem but then hit another one which I have only just solved which was that PhpTools was loading a different php.ini to the one that was showing up in the project settings.
I don't know how it happend, and it may not be something you will be able to reproduce, but it was extremly frustrating and time consuming to find. In my case it was loading the php.ini in C:\Program Files (x86)\IIS Express\PHP\v7.4 but my project settings page indicated that it was using the one in C:\Program Files\IIS Express\PHP\v7.3, so changes I made there didn't show up.
A tip for anybody who is using the tools and is getting weird behaviour: look for the log files in the windows temp directory - in my case it was called PHP73x64ForIISExpress_errors.log.