Yep, and I think that's why the attack in Belgorod (actually the second attack east of the border) is important. If Russia tries to keep the east (and maybe part of the coast - they can't take Odessa, that much is obvious now), not only are they back to the same position they were before the invasion, but how do they intend on doing that? What's the deterrent for Ukraine to accept that as an outcome? What's Kyiv got to be afraid of, invasion? All Russia has left after this is nuclear attack.
I think a big part of the reasoning for Russia to have pulled back from Kyiv, etc. is because for them to have won this war they'd have to give it everything they've got. Their military is in such bad repair and Putin can no longer trust anything he hears from FSB/SVR/GRU, he has to assume that the whole national security architecture is fucked. So they either throw all their resources at Ukraine and leave the Kurils, Abkhazia, South Ossetia, Transdneistra, maybe even Vladivostok (look up who Beijing thinks Vladivostok belongs to!) completely vulnerable, or, even worse, they prove to the world that they are vulnerable to anyone who wants a piece.
Putin is in full on damage control. He realises that no only is he not as strong as he thought, but that he's actually weak and can no longer even trust his own agencies. So, how the fuck, with that being obvious, is he going to hold on to Eastern Ukraine (without using nukes)? What has Kyiv got to lose by throwing everything at the Russian's and attacking across the boarder - and you know that the Americans, British, Swedes, Finns, Czechs, Polish, etc. will be giving them a packet of info to assist.
These massacres of civilians in Bucha and elsewhere are going to hurt Moscow. Going to be harder to keep the money flowing from Germany and for China to hold on with diplomatic cover. Things are tough in Moscow right now. The chance of Putin going the way of Romanian dictators past is higher than it's ever been.