Matt has many other videos on this topic, but that is just the last one that contain information about the change / problem.

Basically Core is removing options for Mempool management and increasing the OP_Return size limit. Knots is an alternative fork of core with the ability of Mempool management and the ability to adjust OP_Return to zero. People behind knots are making this situation look way worse than it seems. (We have bigger fish to fry.) and saying that CSAM is going to be on every node. Even though ways to put the arb data on the chain has been possible even before this whole debacle. Simply because Luke and Mechanic are making alarms of issues that aren't there or highly improbable. Knots is wanting to go the route of censorship with making certain transactions invalid. Also claiming Bitcoin is going to die if we don't run Luke's fork. While some people in Core are being stupid and way to naive in how to handle these things. Even some Core devs sucking on the dick of big shitcoins trying to use Bitcoin for their own gain. A few of them are on a high horse saying that only those who know how to code should have an opinion. While also making it fair game for Shitcoiners to try to ruin Bitcoin for their pump and dump. (Cough) Citrea (Cough) Also Knots is a fork of core mainly maintained by just Luke, all the heavy lifting is being done by Core. I wouldn't recommend migrating to Knots due to Luke's OPSEC history. But if you are building a fresh node then run Knots if you want to have more tools under your belt. I also would say that Core needs to stop fucking with user options on how they want to run their nodes. Theyre just there to fix patches and help fine tune things that people want, not for them to decide what's good for Bitcoin. My two sats is to keep running an older version of Core and wait for the dust to settle on this. But if you really want to be active in this run Knots to manage your Mempool the way you want to. Me I am happy with my version of Core I am using.

Watch Matthew Kratter's Bitcoin University videos on YT on the subject matter. His is always goated.