Now, let's discuss the points that might be concerning with Fabien Lovett, and the first thing I noticed while watching him play is his slow reading. Fabien is often static until he finishes reading the play. That being said, while it's definitely a flaw that needs correcting, Fabien at least deserves credit for continuing his penetration during his reading.
Let me explain: while he is indeed too static in his movement and stays in front of his opponent, he at least tries to push the latter, thus having an impact on the quarterback's pocket. He doesn't just stand there doing nothing as can be the case with other prospects.

I think given the player's profile, you may have guessed it, but with Lovett, we don't have a polished pass rusher ready to dominate NFL offensive linemen. On the contrary, unfortunately, Fabien is a bit too limited in his variety of Pass rush. Most of the time, he relies on his power, like most nose tackles. So, we have some Bull-rush, a lot of Bull-rush, and then some more Bull-rush (Indeed, my friends who are avid fans of "The Lord of the Rings" will undoubtedly recognize my plagiarism of Samwise Gamgee here.)
From time to time, we can see from Fabien a little Swim move or even a shy Rip move but clearly he focuses on his Bull-rush and his Push-pull to collapse the pocket and generate pressure more than really chasing the QB.

His hand placement will also need to be reviewed as it's still quite random, which is a shame because we can see in the footage many reps where Lovett decides to Bull-rush his one-on-one opponent and initially manages to push the blocker back very effectively before his hands, misplaced, slip on the OL's jersey, allowing the blocker to halt Lovett's progress abruptly. It's a real shame. Work could be done on this to truly help Lovett make a leap in his development.

Another issue that bothers me with Fabien is his choice of technique depending on the situation. Think of it as a decision-making problem that we rarely talk about in DL and even more rarely in DT, but it can be important because this decision-making sometimes makes the difference between a tackle for loss for your defense or a touchdown conceded because your DT got blown up in the middle and opened up a huge gap that your LBs won't be able to fill.
These are small errors, but they can be costly if they happen at the wrong time. For example, Fabien tries to execute a Swim move while he is caught in a double team composed of 2 OLs larger than him, causing him to lose balance and get pancaked. Another example is when Fabien is slightly pushed outside by a guard and decides to jump (i.e., change his gap responsibility by abandoning his primary assignment) to rush the QB on the edge. However, against a scrambling QB or a Drawthere's no one left inside, which can lead to a big play. So, attention should be paid to this point.

His age doesn't play in his favor either. Once again, opinions may vary on a player's age, but it's undeniable that most coaches/GMs prefer younger players. The younger you are, the more potential they see in you, the longer you can play, and the more valuable you are in the eyes of the team's key decision-makers. I know for a fact that some teams will let him slide because of his age and prefer to take players who might not be better or fit better into their system, but who will be younger.

Finally, in my opinion, Fabien could also lose some value due to his size, which may not be ideal for the role expected of him given his qualities. At less than 320 lbs, Lovett, who seems to be heading towards a role as a Tech-1 NT (or even Tech-0 in some packages), will need in my opinion to gain a little weight to really be in the best conditions to do the job in the NFL, where the opposition is very different. Moreover, when we consider the strengths and weaknesses of his current game, a few extra pounds won't drastically change his playing style.