L2 -i797 Not received though L1 i797 got approved

My husbands L1 visa got approved on March1st 2020 and he got his i797 approval document. But for dependents we should get also 1797 based on our previous visa extension experience. Does anyone know if there is a rule change on this whether dependents do not get i797 document from 2020? I know its not an important document for dependents or even for stamping. I have seen various forums where they say, that document is not required for visa stamping for dependents. But trying to figure out why has not it been sent or not received.

No, there is no rule change.
The general rule is that, if you are in US and on L1 Dependent visa, which is L2, then you either need to have valid I-797 approval notice for L2 or valid US visa that has L2 on it.
If you are in US, when they apply for L1 extension and you L2 is expiring, employers usually apply for L2 extension too, unless you plan to travel out and get L2 stamping.