Hello Martha, this is Emily.
This is a third party product, whether it is compatible with Windows 11 is determined by the Bamboo pen's manufacturer. In this case, you have already confirmed with them. I did check on Wacom's website and it definitely didn't mention Windows 11, so that can be true.
https://support.wacom.com/hc/en-us/articles/150...
Note: That's not a Microsoft website, but it is the official manufacturer website from Wacom.