Since you have the game on Steam and have played almost 100 hours, I'd recommend verifying the integrity of the game files. I didn't buy it on Steam because I have the pirated version, which is boring for now. I'll buy it on Steam when I get an RTX 4090 PC build to enjoy it at ultra settings. For now, it's boring for me.
If that doesn't work; did you install RDR 2 in an external HDD? If so, does the HDD contain a huge amount of files? Because the same case happened to me with Payday 2.
btw I put Arthur's profile picture because of his badass behavior which looks dangerous but also true and a warrior type who doesn't fear anyone but can fear anyone in front of him with his words. Also, I haven't played all of the missions.