It is always recommended install both Language dependent and independent update ad then run psconfig wizard. Not sure if you can roll back SharePoint update unless you have taken Image level backup of SharePoint Servers and SQL servers
This is an expected behavior in SharePoint. If you are using the content type in a list, you cannot delete it directly from site.
First you have to remove the site content type from all lists & then you can delete it from site settings --> Site content types.
Alternatively, you can hide the content type from list instead of deleting it. Follow below ...
First, you must ensure that you have Full Control permission to support you create a SharePoint Group.
Then, you can go to site permissions page directly using the URL: https://tenant.sharepoint.com/sites/sitename/_layouts/15/user.aspx
You could click on Create Group
Sign in Microsoft 365 admin center as SharePoint administrators or Grobal ...
To create a group & grant permissions, you need a permission level that includes permissions to Create Groups and Manage Permissions. The Full Control level has both.
Also, You can go to site permissions
page directly using the URL in this format:
Check this documentation to create a SharePoint Group.
Office 365 E1 can meet your requirement.
If you want the lowest subscription, Microsoft 365 Business Basic is the lowest subscription that can meet your requirement.
Here's an article for you to know more about the difference between Microsoft Office 365 E1 and Microsoft 365 Business Basic.
Sum up, in a business of less than 300 users for the foreseeable ...
You can create customized Conditional Access policy in Azure Active Directory to specific users to limit access to SharePoint regardless of from managed devices or not.
Reference: Building a Conditional Access policy
There is the same post on the Q&A Forum, I suggest you can follow the progress of the post.
To use this setting, get a subscription to Enterprise Mobility +
Security and assign a license to yourself. Manage subscriptions