Based on what we can see and the description (which, again, may not be telling the whole story):
1. Haynes (LAA) blocks the punt (and we can assume he does not "possess" the ball)
2. Plata (HOU) is the next player to touch the ball. He possesses it and is tackled.

Note when you watch the play that the yellow "Fumble" tag appears. In addition, Plata is credited with a fumble recovery on the play, though no LAA player is credited with a fumble.

In the end, I think that the only retroactive logic that can be applied to the play is that an LAA player touched the ball downfield (i.e. AFTER Haynes blocked it). That could render it a live ball, which is then "fumbled" for Plata to recover.

That is not clear from either the video or the play description, however, so that's why I put it here.

Based on that, have to wonder if the game is treating a block as a possession and fumble?

I can imagine that the game engine treats the block as if it were batted straight down, hit the ground at the spot where the block occurred (behind the line), and rolled. In which case it should be considered a fumble.
A ball that is batted behind the line, but still travels, airborne, and lands beyond the l.o.s. is not considered a fumble and is treated as a normal point as if no one has touched it.
I could kinda understand if the game engine (incorrectly) treated the block as a possession and subsequent fumble. I have no idea how the code is written to treat those instances.

A punt blocked (straight down, behind the line, or beyond the line) is NOT a fumble. Below is the relevant portion of the NFL rules (note that "kickers" and "receivers" refer to those TEAMS, not the actual punter or returner). I've added emphasis to indicate the language that seems in dispute here:

"ARTICLE 2. KICKERS CATCH OR RECOVER BEYOND LINE. When the kickers catch or recover a kick beyond the line of scrimmage, the ball is dead at the spot of recovery, even if a member of the receiving team has first touched the ball.

Item 1. Legal Catch or Recovery. If the receiving team touches the ball beyond the line, a subsequent catch or recovery by the kicking team is legal, but the ball is dead. In the event of such a catch or recovery, it is first-and-10 for the kickers, or if the ball is caught or recovered by the kickers in the receiver’s end zone, it is a touchdown for the kickers. (7-3-1-d)

Item 2. Illegal Catch or Recovery. If the kickers catch or recover a kick beyond the line that has not been touched beyond the line by the receiving team, the ball is dead, and it is first-and-10 for the receivers at the spot of catch or recovery (see 11-4-2 for missed goals). If a kick from behind the line is touched by the receiving team behind the line, such touching does not make the kicking team eligible to catch or recover the kick beyond the line. "

Given those rules we either have:
A) An instance of item Item 1, as I suggested in an earlier post, in which the kicking team recovers a ball after it has been touched by the receiving team. In such a case, the receiving team would have "possessed" it, even if just by a touch and it could be recovered by the kicking team. If so, then the descriptions and playback of the game just didn't show that, so that would be a bug that the developers may want to work on.
or
B) An instance of Item 2, in which the receiving team touched (blocked) the kick behind the line and it was recovered by the kicking team beyond the line. In that case, the receiving team would get possession first and 10 from the spot of the recovery. If so, then that did not happen in this case in which case there's a bug in the engine that is misapplying the real life rule.

It seems to me that one of those scenarios must be true. What is shown and described does NOT constitute a fumble, according to the rules, regardless of where or how the punt was blocked.