Just had a peek and it certainly looks unusual, as though the 737 is flying dangerously close to the ground.
I think it's down to an optical illusion making the aircraft look like it's flying low while it could be at cruising altitude.
Here's an interesting article on the sort of rainbow looking shadow cast by the 737: https://www.gearthblog.com/blog/archive ... ffect.html
The closest airport would be Derry Airport which I'm pretty sure Ryanair operates out of- so it could indeed be a 737 perhaps on departure out of the airport before making a right turn towards the UK- no normal 737 would be making a transatlantic route unless it was a 737 max, which are currently grounded due to MCAS problems that we've probably all heard of. My guess would be that it was climbing to cruising altitude before turning right.
That being said, the white livery might appear to be an unmarked 737 which could be unaffiliated with airlines- used for reconnaissance at low altitudes?
I say this as last year, a large enough propeller aircraft flew over my house at a scarily low altitude, no more than 70m! A google search told me it was being used for imagery so perhaps this plane could've been used the same way?
On that topic, look up "St. Maarten airport landings" on YouTube, you will see a very unique beach where fishing would be impossible due to heavy aircraft passing literally metres over your head!
Anyway there's my 2 cents as an aviation freak, I'm probably overthinking this tremendously!