Betta Fish: Do I need to use flourish excel?

Hello fellow betta people 🙂

So i recently purchased some new more aquatic plants for my fish tank. Tank renovations , big things.
(Please ignore the yellowish tint- it is because of the wood & totally under control, in the process of water cycling)

The person at the store asked me how many fish I have and how big of a tank. It is just my one betta in a 10gallon tank, and she said that in this case I should use excel flourish because with just one fish and this many plants they can produce too much CO2 (or oxygen can’t remember tbh) and that I should use this to balance it out.
I have been reading that it is completely safe, but some people online are saying it killed their fish. I do not want to harm my little guy, i want him and his plant companions to thrive and live in harmony together.

My questions are should I use this? If so, how often? I’m not crazy about adding something into the tank everyday unless it is dire, and in that case i’d assume it would be best to just take some plants out? Is this too many plants?
Maybe she was just trying to sell me, any advice/suggestions are welcome and appreciated greatly!

Thank you and I wish everyone & their pets good fortune!