Looks like the mortar joint cracked, so what I would do would is remove a couple of those bricks, look closely and see if there's anything suspicious behind them.
You also might want to invite any person you might know who works in the masonry field.
And of course, if you don't know anyone, then youu might call for a free estimate regarding what's up with it. ( Having bricks removed allievates the free estimate from saying " I dunno, we're gonna have to remove a couple of bricks to see what happened behind there."
I would believe any masonry contractor would want to look behind there as well.
If this is nothing more than a weak mortar joint, you might want to tackle this yourself with a product called Sika Bond, which is a mortar colored masonry construction adhesive
( comes in a caulking gun tube ) which is super strong. And will bond any type masonry.
Sika Bond can be found at both Lowe's and Home Depot.
Good luck 👍