SS wages different from W3 to total of 941s in 2020

Have a client who was informed by the IRS that her SS wages on her W3 differed from her 941s by about 44K.  My first thought was COVID, but they only paid about 13K in COVID wages.  She has been through the W2s compared to the Quarterly Report YTD for each employee and can't find a difference.

I'm not sure where else to begin to look.  Don't the W2s and 941s pull their information from the same file?