“The Old Guard” has an interesting idea.
A group of sorta-immortals discovers they’re sorta-immortals. They band together to do good and fight the good fight and generally embrace cliched notions of heroism.
They are also very sad and not-so-secretly long to die.
The fact that these heroes are quite old (some have been around for centuries, others, millennia) provides fertile ground for all sorts of stories. Trouble is, the story they chose to tell is just a series of set pieces. It’s not a cohesive narrative.
“The Old Guard” is set up to be a franchise, so perhaps further depth is forthcoming.