I mean, it’s true tho. Ukraine has been independent from Russia for less than 40 years, while California has been part of the US for damn near 200 years. Russia has more of a claim to Ukraine than Mexico does to any of its former territory in the US, yet no one is calling Russia’s invasion of Ukraine justified
I think I see some validity to OPs point but I would argue that the situation isn’t exactly the same as arguably Ukraine (as a people) choose to leave the USSR while Mexicans were pushed out via a war. The people who live in Ukraine haven’t gone anywhere so there is no “theft” of land. Culturally the Ukrainian people have long existed as a people whose lived there for a very long time and choose to self-govern
You’re not fully wrong but also not fully right. The concept that land can be stolen also implies the idea that land belongs to a people because their cultural group was there first which doesn’t seem exactly right either. That doesn’t change that a wrong doing in the near past affects people today. Perhaps is stupid to say it was stolen but it also isn’t untrue to say as it was taken out of conquest