Open x1.odt
0: select 'a+x1', hit b, get b as subscript --unexpected
1: select 'a+x' (which contains no subscript), hit b, get b as subscript; I
expected only the 1 to be subscript.
2: select dd, hit c, get unsubscripted c --inconsistent with 1 and 3; because
not at BOL?
3: select 'mmm', hit n: get n as subscript: the subscript effect was copied from
the 3, but not the font --n is arial, like mmm.
select mmm3, hit k: get k subscript, TimesNewRoman (like the 3)

The parameters (font, size, typeface,  etc) of the 1st char of the selection
should take precedence
May be related to Issues 86697, 86942