I've been seeing a strange puff of smoke about halfway down the runway in front of the aircraft after touchdown. Has anyone else had this happen???

Me too sometimes.

There is an FX that blasts dust or rain off the runway behind as the the aircraft rotates for take-off , but I can't see how that could be showing in front ..

It's fx_lit3_Steam if you want to disable it.

Yes, it looks like smoke of catapult but 50 ft behind of front our armed Fighter . Dont know what is it too.
Maybe this:

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I've been seeing a strange puff of smoke about halfway down the runway in front of the aircraft after touchdown. Has anyone else had this happen???

Does this happen when you are landing away or just when you land back at the same runway ?

If it's only the latter my guess is it's your take off dust ! Its set to show below 10ft and over 170kts so if you are landing a bit fast it must be triggering the ending of the spray that was cut short on take-off .

When I land back at the same airfield....,sounds like you're right