disabling SMB1 everywhere?

After reading the 2 below articles:

https://docs.microsoft.com/en-us/windows-server/storage/file-server/troubleshoot/detect-enable-and-disable-smbv1-v2-v3

https://techcommunity.microsoft.com/t5/storage-at-microsoft/stop-using-smb1/ba-p/425858

I've discovered our DCs, hypervisors and a few other servers have SMB1 enabled. I joined this org a few months ago and have inherited this infrastructure. I know I need to disable this but the org runs a lot of legacy apps etc. so I just want to understand what the risks are of disabling this. What features and compatibility issues are likely to happen?

EDIT: Additionally, is this something that requires a reboot after disabling, or should the removal of this feature occur out of hours for any reason? I am keen to shut it off ASAP providing there's no real risk of doing so.

Thanks in advance :)