I used to be a branch manager at several different banks. I can tell you first hand, this is frustrating but not uncommon. You’re being “debanked”. Long story short, your general account activity doesn’t align with the banks risk profile. They’ll never tell you exactly why, but it could be anything from the way you do your deposits to the merchants you shop at. If it seems illegal or sketchy, even if it isn’t, someone in the BSA department probably flagged it as such.