Look into the curved wall, freeze and fire with the freezeframe rocket launcher, then SHORTLY tap a dive input: jump and slide IN RAPID SUCCESSION.
Did you copy a previous save file to this patch's directory, because that's what caused it to not work in my case.
I've had the same issue with the sharpshooter release patch. All I know is that P-ranking every level again fixes it.
I suggest trying the zoomies patch (released on 8/16/22), there's a bunch of rocket clips on that patch for Any%, and I believe that the weopon wheel also slows doen the game.
Maybe try to slide a tiny bit later than jumping.
I find doing the inputs at the same time a bit inconsistent.
Sometimes holding the buttons for too long messes it up too, it's really just a short tap.
I made a little tutorial for you. I am not an expert, so if anyone wants to add to this, be my guest.
I tried finding an OOB in 0-4 on current patch, but I don't know if it's optimal. I posted it on YT, so you can see it. I don't know if it is optimal for runs on current patch, because the inbounds level is already quite optimized, but the clip allows for an ultraboost, so that compensates for the time it takes to get OOB.
Anyways, here is the video: