TAX | Capital Gains

Hi, anyone here has reported over capital gains on top of your current employment earnings? I've been trading via Revolut, but since the entity seats outside of Poland, I wonder whether the tax office has access to my trading activity. Specially that I am thinking about migrating to IBKR.
I know that EU consistently push towards institutional data sharing, but I wonder if it time to go down that road or wait for a letter from the tax-office. Has anyone went/thinking about this? I would also appreciate any recommendations for a tax-advisor. Dzenki!