Ultimately, your problem is XAMPP itself. You can extract the ZIP file with 7-Zip as a temporary solution.
They are using the non-threaded PHP SAPI as an Apache module. However, Apache needs all its modules to support threading since the default Apache MPM is multi-threaded. The discrepancy causes thread concurrency issues which manifest themselves in different ways including the inability to open files for reading or writing. The problems only happen when there are a lot of requests in a short amount of time which typically only happens if you have some kind of automation running, e.g. taking / restoring a backup, indexing article text, test sending a newsletter using a local mail server (e.g. MailCatcher or similar), and so on.
I have explained those finer points in my blog back in 2018, see Improve PHP performance on Windows. It's driving me nuts that XAMPP has not caught and fixed this problem in nearly twenty years. Argh! Every couple of months we have a client who, like you, has hit that brick wall.
For this reason I always recommend WAMPServer to our Windows users or, better yet, set up their (see IIS development server for PHP on Windows 10 for example if you want to use IIS; I have an older tutorial for Apache which is mostly okay, see Apache, MySQL, PHP server on Windows with multiple, simultaneous PHP versions).
Nicholas K. Dionysopoulos
Lead Developer and Director
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