In his 2/21/2022 address justifying Russias invasion of Ukraine, Vladimir Putin states the rationale as Ukraine being an integral part of Russia connected by history and blood relations. China feels the same about Taiwan. If China uses force to take over/back Taiwan, should the US be involved in supporting Taiwan?
Note that the US is bound by the Taiwan Relations Act to defend Taiwan.
Taiwan Relations Act (Public Law 96-8, 22 U.S.C. 3301 et seq.)
https://www.csis.org/events/ukraine-and-taiwan-parallels-and-early-lessons-learned
https://www.washingtonpost.com/world/2022/03/04/taiwan-ukraine-russia-war-china/
https://www.military.com/daily-news/2022/03/11/how-russias-invasion-of-ukraine-shaping-chinas-plans-taiwan.html
https://www.washingtonpost.com/opinions/2022/03/24/ukraine-resilience-has-inspired-taiwan/
https://www.wsj.com/articles/in-taiwan-putins-war-in-ukraine-stirs-new-interest-in-self-defense-11646402103
https://www.cfr.org/backgrounder/china-taiwan-relations-tension-us-policy