This is normal. Background checks - of the sort where they actually try to contact old employers and verify employment history - are a total joke, especially ever since everyone in HR started to 'work' from home. I've seen background checks come back a full month after the person had already started their job and had access to all of the internal systems and were collecting paychecks. Most companies won't deny you the job just because the background check is taking a long time. And if they did, that would be a bad PR move for them I think.