same. its basically a device which, over-used, becomes a manipulative gimmick to 'manufacture' suspense, keep people watching. Its endemic in TV series now, a staple. Again, used adroitly, can be a nice context-switch - but, for example, I'm watching Severance - they use flashbacks mainly to manipulate the audience, imo.
I thought the big issue was the fact that the writing and acting quality has really sucked in the past decade. Over half of the tv shows that have come out since 2015 had scripts that were on par with what an immature teenager would write, and many of the actors weren't that good at their jobs either. The finest examples of such crap could be attributed to the CW and many Streaming services.
I remember how with "Once Upon A Time," the flashbacks actually worked well with the different episodes, because we could see a parallel story that happened in the past with the fairy tale world, and how it related to what was going on in the present in Storybrook. However, it became pretty obvious after a few episodes into Season 1 that this series was being written by very stupid, childish, immature writers, and after season 2, I got really sick of the memory loss trope. In fact, it got old after just Season 1. By the time Season 4 came about, I was extremely annoyed, not to mention angry over the writers sabotaging their own storylines, or elevating unlikeable characters over everyone else. Then when I heard what happened in Season 5 (before seeing it), I was done and never watched the show again. I read up on what happened after I quit watching, and it frankly didn't get much better, though it was nice hearing that they stopped Emma from being a Dark One and she married Hook at the end of the series. The show's two spin-offs were just crap that even a kid wouldn't watch.
I completely agree, especially when the movie itself contains a riddle or mystery or something like that, which is revealed piece by piece not in the movie but in flashbacks of a few seconds every 10 minutes or so during the movie.
There's one movie (forgot the title) where a woman receives a letter on start from a girlfriend she has had long ago in school, where the movie itself is for over 90% an extremely boring show of the all day life of that woman, while every now and then in the movie a speakers voice reads another line from that letter which reveals the story that happened long ago.
They could have made it a 15 minutes short movie and it could have been quite good, if they had red the letter in full on start and then show the last 10 minutes of the movie.
One show that used flashbacks well was "Damages". They were quick and constantly revealed a twist in the story that made the audience think differently.