Does Square or Chase have trouble with their trademark? It's not a big deal.

Single words are often used when they don't really have much to do with the underlying product (Apple, Amazon, Mint, etc.) because it can be "branded" for that market.

But with Wise, for example there is already a MoneyWise, BudgetWise, etc., so "Wise" by itself may have issues with those other existing businesses.

Trademarks are granted within specific fields, so they won't have any trouble defending it against people providing related goods and service (banking/finance/transfers) using a similar mark. The won't be able to defend against someone else using "Wise" in a different field (say, an education platform) but that is as designed. It is unfortunate that large corporations overzealously "defend" their trademarks against all usage of the trademark even in unrelated fields, that is abuse of the process and not how the law was intended to work, they basically drown you with lawyer fees.

that's a rough one to defend when this exists: https://www.wise.us/