Required to disclose other sources of income?

Incoming FT analyst here. I know my bank's compliance requires us to disclose any other sources of income we have, but I have also read online that legally you do not have to disclose.

I started a car Tiktok channel before I had my internship last summer and compliance approved it as long as I did not mention the firm or get paid anything, which was fine over the summer. Recently I was offered a good chunk of money to promote a brand for 1 year, which will be still ongoing when I start FT this summer. The money isn't crazy but I'm generally a big fan of this brand and want to get to try their new parts for free, plus I don't start working for 6 months and money now would be nice.

I'm wondering if I accept it and have to promote the brand for the full year, if I would be fired or reprimanded at work for this (if it's true that legally I don't have to disclose other sources of income to them).