If you find out there is a similar trademark registered in the market of your choice, it may cause some issues that might temporarily stop your application or prevent you from obtaining a trademark registration altogether.
The risk includes receiving an "Office Action" or an "Opposition" during the process.
An Office Action is an official decision issued during the examination period by the examining attorney in the US, China, Canada, and Australia. If the examiner finds a confusingly similar trademark, either pending or registered, they will issue an Office action. You can respond to the Office action and try resolving the issue if possible. In most jurisdictions, the examiner doesn't outright stop the application if they discover a similarity, but they will notify the owners of similar trademarks - more on that in a second.
After the examination, the application proceeds to the opposition period. The length of the opposition period depends on a concrete jurisdiction. Here, the owners of similar trademarks (including but not limited to the ones notified by the examiner during the previous stage) can come forward and raise an opposition against your application.
If they do, the IP office will notify you. You can then reach out to the opposing party and try resolving the issue amicably. If you don't reach an agreement, you will be asked to present evidence to the IP office defending your brand. The examiner will make the final decision.