Hi Karen, I'm John, a fellow Microsoft user like you.
I understand you're having issues with dual booting, and I'm here to help. Microsoft has acknowledged the issue with the update and has posted a mitigation, which you can find at this link: "August 2024 security update might impact Linux boot in dual-boot setup devices" https://learn.microsoft.com/en-us/windows/relea...
If you've already installed the August update, you might want to uninstall it by going to Settings > Windows Update > Update History > Uninstall updates. Then, apply the steps under "Scenario 1" in the workaround mentioned in the link above and continue from there. Or try "Scenario 2" if applicable.
I really hope this information is helpful. If you continue to have issues, please click "Reply" below and let me know.
John J.D.