All the R1b subclades we have seen on the bronze age steppes in other papers are descended from M269. So it would make sense if these were under M269 too.
But i am not ruling out that V88 could have been there somewhere too. Although it has not been found there yet afaik.
I don't know how many M269 have been found to date. But just because it is positive for M269 does not mean that it can't be something further downstream like Z2103 or L51.
You know, like the J2b in bronze age Jordan a few years ago, which later turned out to be J2b1 when people checked out the bam files.
This is the excerpt where you can see that R1b1a2 actually means R1b-M269, and that R1b1a2a means R1b-L23 in this paper:
KBD001 could be assigned as R1b1a2 based on the mutations: PF6399:C->T, M520:T->A, L773:A->G, PF6430:T->A, L265:A->G, L483:C->T, PF6434:A->G, PF6438:C->T, L150.1:C->T, PF6475:C->A, CTS8728:C->T, L500:C->A, PF6482:A->G, PF6495:G->A, PF6497:C->G, PF6505:G->A, M269:T->C, CTS12478:G->A. We note that this individual also has a downstream mutation L23: G->A determining haplogroup R1b1a2a, but this mutation might be caused by ancient DNA damage.