Is It No Longer Allowed?

That's not true. Wherever you saw that or whoever told you that is misinformed.

"The NFL rule book forbids players from partaking in “prolonged or excessive celebrations” and “players are prohibited from engaging in any celebrations while on the ground.” "

There is no written guideline for prayer in the rule book, but in practice, exceptions are often made for a player’s expression of their faith.

I didn't think they ever could prey on the field - although I understand sometimes it seems like they are.

Tom Brady is preying every week (on the rest of the NFL).

I guess you are right - I did a search for Tom Brady preys and then Patriots prey and a whole slew of articles pop up stating just that.

So I guess it is allowed --- well actually roger may try to charge Brady on preying on the other teams....

There was a very recent case where a high school coach at a public high school was leading a group prayer on the field for his team. This has not been allowed for years, the coach refused to stop, he was suspended. Individual players praying on their own has always been fine.

This is about NFL games, if I'm understanding the query.

I think Engineer is simply alluding to a probable source for the OP's misunderstanding.