$350 is a DIGUSTINGLY low sponsorship rate, considering both the number of impressions they offer and the time spent covering the product. I can assure you mid-size YouTubers charge around that or more for those 30-second ad reads at the start of unrelated videos; hosting hours'-long dedicated streams showcasing the product and associated merch, broadcast to a large live audience AND posting a static vod reaching a secondary audience offers much, much more value to the advertiser than that.
What's happened is it being a company-wide collaboration rather than specific talents arranging the brand deal themselves has meant the negotiated fee has been split between more people, so everyone's getting shortchanged.