line 1a on 1099 is total dividends which consists of qualified dividends reported on line 1b and non qualified which isn't reported on the 1099 though the broker may provide a supplemental schedule. line 2a-d are capital gains dividends. line 3 is non dividend distributions (return of capital) lines 2 and 3 are not included in line 1a or 1b. in addition there may be an amount on line 5. these are part of the total and nonqualified dividends
if line 1a went down and line 1b went up then line line 2 or 3 would normally would go down. that is either a capital gain dividend or non dividend distribution has been reclassified as qualified.
far-right-wing
put another way line 1b + nonqualified dividends + 2a + 3 = total dividends (not reported on 1099 but may be shown on supplemental schedule) so if 1b goes up other amounts (maybe total must change)
since we don't know exactly what changed can't tell you or even estimate the amount your taxes might changed
