All I know is that when matter and antimatter particles annihilate, what that usually means is that they become photons, so that their rest mass - what we usually mean when we say matter itself - is gone, having turned into pure energy, mainly gamma rays I believe.

The other part that you allude to, has to do with how at the quantum level, processes are time-symmetric or time-reversible, look exactly the same if you view their behavior forwards or in reverse, you cannot tell which way it’s going. Antimatter behaves just like matter, but from our perspective like an egg un-breaking, or a car un-crashing, or an ice cube un-melting.

What’s puzzling me is how photons, other bosons like gluons or majorana particles are supposed to be their own anti-particle, how does that affect their time-related behavior and interactions with themselves and other particles, I have no idea… at least not yet.
In fact, I hadn’t even thought about this strange question until just now, and I love it!