Normally the Brayton cycle denotes T3 as post-combustion, pre-expansion.
That may be true in some conventions, but hardly universal. Over a 33-year career I've seen the numbering system change every few years.
But one thing that has remained (nearly) the same is P3 and T3 - it's compressor exit = combustor inlet. (In very new engines it may be called P30 & T30 - to permit a finer breakdown, pre- or post-diffuser)