The one thing that prevented this movie from being a masterpiece was....
....the de-aging cgi. It was a failed experiment. At times, it took me out of the movie, the cgi faces (and the body movements that didn't match the supposed age) were a little too distracting and unconvincing. Using both younger and older actors (instead of just geriatrics for the whole movie) would've been the correct thing to do. I like this movie a lot, but Scorsese made the wrong call to go with cgi instead of using younger actors.
"What's the problem, kid?" "You're back in business, kid" "You know how strong I made you?...You know how strong?....You're my kid" Pesci said these lines to De Niro in the movie....and they're both the same age! It's ridiculous that we're supposed to believe that Pesci was some sort of father figure to De Niro. Too far fetched to be taken seriously. I thought Scorsese's movies were about conveying realism. Well, those scenes were completely unrealistic, it took me out of the movie.
Pesci's age was fine and convincing for his role in the movie. My issue is mainly with De Niro (76 years old) and Pacino (79 years old), these guys were too old and the cgi de-aging was not convincing or believable in any of the scenes with younger Frank Sheeran and younger Jimmy Hoffa. Luckily (and thankfully), these guys are great actors (both are acting legends) and it didn't ruin the movie....but, it was the one thing that prevented this movie from being a masterpiece.