It’s not disinformation, but it is partial information. They’re revealing enough information about their defense plans to make it clear that any invasion attempt on Poland will be costly. Russia does not have limitless resources. If they think they have enough resources to fight a war on two fronts, then it is in Poland’s best interest to both bolster their defenses, and let the enemy know they’ve bolstered those defenses in hopes that it changes the war cost equation enough for Russia to realize it is not favorable decision anymore.

It’s the geopolitical equivalent of finding out there’s been multiple breaking and enterings in your neighborhood recently, so you go out and buy a gun and place a “this house defended by Smith & Wesson” sign out front. You don’t tell them where in the house the gun is. You just give enough information for them to rethink their choice. The goal isn’t to defeat the burglar. The goal is to not get broken into.