Cant access bootcamp after resizing partition

You cannot resize the partitions when using Windows Bootcamp. If you need to modify the sizes of the partitions you would need to use Bootcamp Assistant to remove Windows, then start over by reinstalling Windows using Bootcamp Assistant.

You can try to use Disk Utility to reverse the partition change you made to see if that will restore Windows to boot again. Even if Windows is no longer bootable, you can then try using Bootcamp Assistant to remove Windows in order to reclaim the partition used by Windows. If this is successful, then just use Bootcamp Assistant to reinstall Windows again.

Otherwise the easiest way forward is to first make sure you have a good backup of your data. Then start over completely by performing a clean install of macOS by erasing the whole physical drive, followed by reinstalling macOS & restoring from backup. Then you can use Bootcamp Assistant to reinstall Windows.

The problem is the first Windows bootloader is located on a hidden EFI (aka ESP) partition.....which then points to a secondary boot file on an actual Windows partition. The problem is you have moved the location of this second Windows boot file with adding an extra partition. Theoretically you can boot to a Windows installer and fix the problem, but even on a dedicated pure Windows system (non-Apple) it is not always easy. Being on a Mac with macOS partitions just complicates things even more. Plus with a Mac, you may find Windows needs some Apple drivers in order to work...I haven't used Bootcamp in years, so I don't know how it works in this regard. I don't know if you can access the Windows repair mode which years ago on a standalone Windows' PC would be accessed with F8, or F5, or such key, but I think access to this mode was changed with Win10 (I rarely work on Windows systems these days).

Windows has never, ever, played nicely with other operating systems when dual booting....not even with other Windows installations. I used to be able to fix Windows boot issues somewhat easily back in the day, but the last few times I tried to fix Win10 boot issues I was unsuccessful (even on a regular Windows only PC). Usually if the automatic Windows repair tool (in Automatic Repair mode) does not fix it, you will need to start using command line utilities to try to figure things out and repair the boot sequence. It may just involve editing a Windows boot configuration file to point to the proper partition, but it is not always easy to figure out how to properly edit this file even with the Microsoft app BCDEdit.

https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/bcdedit-command-line-options?view=windows-11