If they really wanted to flex they should have taken the capitol within a week like they told everyone they would.

I don't know if you've been following the war from the Russian side at all, but Chechens have been used on pretty much every front except (maybe) Kherson: They were in Mariupol, they have been in the Donbass and they were in the last cities of the Luganks oblast last week. About a month ago the Russian MoD said that they wanted to use the DPR and LPR as occupation forces while the Russians would have taken care of the frontline.
Strategically it makes sense to me because the DPR was getting shreked during the winter and couldn't do much of anything without Russian support