Warning: The following contains SPOILERS for Batwoman Season 2 and the Season 4 premiere of Black Lightning.
The Crisis on Infinite Earths event was meant to tie the various shows set in the Arrowverse closer together. However, the current seasons of Batwoman and Black Lightning seem to be doing their own thing and ignoring the rest of the shared universe, leading many to wonder if there has been some kind of retcon between seasons that have yet to be fully explained.
The final chapter of Crisis on Infinite Earths established that the parallel worlds which served as the settings of all the superhero shows on The CW had merged together into a single world, dubbed Earth-Prime. It also teased the formation of a proto-Justice League that would unite to face those disasters (like the Crisis) too big for any hero to deal with alone. The implication was that there would be more interaction between the various Arrowverse series and while there might not be more crossover events and cameos, there would at least be an acknowledgment of the new shared reality, such as Supergirl's secret identity of Kara Danvers interviewing Batwoman.
This idea seems to have been abandoned heading into 2021, as all of the Arrowverse series to date seem to be doing their own thing and ignoring the shared setting. The setup for Batwoman Season 2, for instance, saw Kate Kane disappear mysteriously after her plane suffered a malfunction while preparing to land in Gotham City. Before it was revealed that Kate had been abducted by the mysterious outlaw queen Safiyah, many wondered how Kate could get lost during a plane crash given that she had just been visiting Supergirl in National City. It seemed unlikely to many Arrowverse fans that Kara would not have been keeping an ear-out for her friend's plane with her super-hearing, just in case there was trouble. This seems even more likely when one considers that it was her sister Alex's plane having problems, which pushed Kara to use her powers in public for the first time and set her on the path to becoming Supergirl.
The premiere of Black Lightning Season 4 had similar problems. The story of Jefferson Pierce and his family picked up one year after the events of the Black Lightning Season 3 finale, where Jefferson and his family testified before Congress regarding the crimes of the American Security Agency (ASA) against the people of Freeland, Georgia. It was revealed that Jefferson, deeply depressed after the violent death of his best friend during the Season 3 finale, hadn't suited up as Black Lightning once in the past year and that Freeland was being torn apart by gang violence and rogue metahumans. Anissa and Jennifer Pierce (aka Thunder and Lightning) were doing the best to keep the peace in their father's absence, with the support of their mother, Dr. Lynn Stewart, and Jefferson's mentor, Peter Gambi. Yet they were fighting a losing battle and even the return of Jefferson's archenemy Tobias Whale couldn't spur him back into action.
Granting that the focus of the series had always centered upon the Pierce family and the Freeland community, the Black Lightning Season 4 premiere started in a drastically different place than where the show seemed to be heading after Crisis. The premiere said nothing about a special school for the metahuman children created by the ASA's experiments, which had been approved by Congress in the Season 3 finale; a project that sounded tailor-made for Jefferson Pierce's talents as a mentor to at-risk youth. Most of the Season 3 supporting cast was also oddly absent, including the Arrowverse versions of Technocrat and Geo-Force who had joined with Jefferson and his family to create a team, not unlike The Outsiders.
It's possible these changes were born of necessity, both due to how Batwoman had to change its storyline to accommodate a new leading lady and the COVID-19 shooting restrictions that led to the cancellation of a crossover between Batwoman and the new Superman and Lois series. Black Lightning faces similar challenges with crossovers as the only Arrowverse series not filmed in Vancouver. Despite this, it is still disheartening to think of what might have been and to see Black Lightning come to a close before Jefferson Pierce was acknowledged as one of the first and greatest heroes of Earth-Prime.