Case transferred from field office to NBC

[FaAh]

Hi, my I 130 is approved and I faced the I 485 ( adjustment of status) interview in Dallas field office on May 2022 but no decision yet.
Recently I contacted USCIS and they told me that my case is transferred from field office to National Benefit Center (NBC) .
Anybody faced similar situation? Why was my case transferred to NBC ?
thanks