The neat thing about having strong nijisister fanbase aside of being annoying psychos is that there are people who actually timestamps and explains what exactly happened.
For context, Luca in that session wanted to fulfill an objective that he wanted which is getting his ass chased by the police (both the AI police and those that roleplaying as police, if I get this right), so he decided that his plan (4:37:35 on the VOD) would be him stealing several cars up to like, 10 or so, drive it into a police station's parking lot, and then blew it up before bailing out. One of the later timestamps mentioned that the cars he stolen from NPC went poof, and he decided to actually ask other niji talents (including Tsukino Mito herself) to help him fill the police station parking lot with cars for him to blew up.
And as of the reason why it's his last NijiGTA stream?
The server was closed on 24th after 10 days of server activity. That vod is from 19th, so he likely decided not joining it during the last few days of server activity since well, his objectives were complete or that he simply has no time to do it again, especially since from the looks of it, Luca is streaming sporadically and the 18th/19th was the only time where he was able to actually play back to back without issue.
Honestly this felt like nothingburger bullshit and not really an L material.