While logged in to myUSCIS, go to the url https://my.uscis.gov/account/case-service/api/cases/"your case number here" making sure to put your case number at the end. It will show a record of actions taken on your file in the form of event codes, including events that may not show on myUSCIS. An explanation of the codes is available here: https://niem.github.io/model/4.2/scr/BenefitDocumentStatusCategoryCodeSimpleType/index.html
My I-751 was received 3/31/2023, and actively reviewed 4/7/2023. No other updates on myUSCIS since then. But the API data shows event code FTA0 on 01/08/2025. FTA0 is Data base checks received, which I understand refers to background checks by other agencies, which are done in batches of applicants. Knowing this doesn't change the fact that I'm still waiting for the next step, but some information about the process is better than none at all.