SharePoint Online list unique permissions

Hello Community

Please could you help me to clarify information related to SharePoint Online list unique permissions.
1. Does the unique permissions limit also applies to list versioning? For example, I have one list item with two versions. Does it mean I have 1 item with unique permissions or three items with unique permissions?
2. I know that the list SharePoint unique permission limit for list is 5000 items and that it can be extended to 50k. Does the 50k also apply to SharePoint online? Are there any common issues related to the procedure? And where can I check the current limitation for my Office 365 tenant?