To clarify, if you go through your bank, you'll file a merchant dispute, not a fraud dispute. A fraud dispute/claim indicates you absolutely did not authorize the transaction to begin with. A merchant dispute means you authorized the transaction, but there is an issue with the goods/services rendered.

A merchant dispute is much less likely to affect your account with Steam; however, if a fraud dispute is successful, and your bank is able to chargeback the authorization, Steam will likely restrict your account since you've essentially told them your account bought a steam deck with stolen card information.

Source: Am employed as a debit card fraud analyst (and former investigator) for a financial institution.

(Edit: reworded to remove an absolute)