Halo CE's hit registration/hit detection on the MCC has always been off since the inception of MCC because it's based off of the botched Gearbox PC port of Halo CE and not the original Xbox version of Halo CE. Gearbox botched the PC port of Halo 1 and 343 botched the MCC version of Halo 1 by using the botched Gearbox PC port of Halo 1 instead of the original Xbox version of Halo 1.
To answer your question as far as I'm aware 343 hasn't changed anything recently relating to the netcode/networking/hit registration/hit detection for the MCC version of Halo CE. The last major update for the MCC version of Halo CE that I can think of was back in June of 2019. The last major update for the MCC version of Halo CE that I can think of removed the auto-aim and red reticule AKA bullet magnetism on the Rocket Launcher to align with the original Xbox version of Halo CE.
- How Combat Evolved was downgraded on MCC | How the original vision is being lost to time
- Just how I remember Halo 1.
To follow up on this, in 2014, major 343 execs performed video interviews with major gaming networks and were quoted as promising halo CE to be exact quote "just you remember it." Halo CE experts were in touch with 343 before launch telling them to not use the gearbox port or they would regret it, and those promises in the interviews could not be fulfilled. 343 used the gearbox port anyway and have dealt with the bugs ever since.
After years of not fixing bugs, living up to their promises, or using the Xbox version of H1, 343 decided that instead of fixing the game and taking advice from people who play CE, they would ignore and shun the people who want to see CE fixed, and continue to use the gearbox version.