Pure electoralism. Once they secure themselves they’ll soften their position.

I think you overestimate the rationality of government decision-making.

they already did

Kyiv-Warsaw talks continue in bid to resolve trade dispute

Ukraine’s agricultural minister, in a phone call with his Polish counterpart, has agreed to work out a solution to a trade dispute that is in the interests of both countries, the Ukrainian agriculture ministry said on Thursday.

A US official who recently visited Poland dismissed suggestions that Mateusz Morawiecki’s comments were a sign of cracks in Western solidarity with Ukraine.

The official, who spoke to Reuters on condition of anonymity about the Polish prime minister’s comments, said:

We’re all human and there are moments of tension... But that doesn’t mean that there’s going to be some dramatic shift in alliance unity or even Poland’s fundamental position and determination to support Ukraine for as long as it takes.

https://www.theguardian.com/world/live/2023/sep/21/russia-ukraine-war-live-updates-zelenskiy-biden-kyiv-kharkiv-cherkasy-death-toll-strikes

Why would they? Ukraine did its job of bleeding Russia militarily so it stops being a threat to Poland. Now they can discard them and the more gets destroyed the easier for Poland to sweep in afterwards and get some pieces of the cake when rebuilding.

The polish government never cared about Ukraine.