Many Roblox anti-cheats check for sudden velocity changes or position deltas on HumanoidRootPart:

If you set CFrame = newCFrame, the delta position (dx > 50) flags a teleport kick.

Sub-Tick Tween Teleport Bypass:
Instead of instantaneous teleportation, tween the CFrame across 4 consecutive RenderStepped frames (12.5 studs/frame). The movement velocity stays within the allowed physics thresholds (< 50 studs/sec), but the player reaches their destination in less than 60 milliseconds with zero server flags!

Micro-tweening is the best way to bypass delta-distance sanity checks. Works on big titles like Prison Life and Blox Fruits.

Smart physics exploitation.