/t/ → /p/
The plosive alveolar /t/ becomes a plosive bilabial /p/ when it’s followed by a bilabial sound, such as /p/, /b/ or /m/, because of assimilation. The change only affects the place of articulation, but the manner of articulation (plosive) and the voicing (voiceless) remain the same.
/t/ (followed by /p/, /b/ or /m/) becomes /p/
And here are some examples taken from real life: