Since I see a developer account active here, I am posting this.
When you jump on an inclined surface you should be moving in the direction of negative slope without any initial movement vector. (First is CSGO 64 tick for comparison)
Edit: Some poeple are pointing out that this is to fix jump throwson inclined surfaces. Let me be perfectly clear in CSGO as well if you just jumpthrow you will not move on low angled slopes like this one. This happens only after you perform multiple perfs. You can jumpthrow same spot no issues unless you spam jump perfs repeatedly.
This behaviour might* be responsible partially for abrupt ramp movement stoppages.
Kindly have a look u/csdev_valve
Best Regards