This is just someone's opinion found on the Internet, and it doesn't give a source for the "IRS guidance."  However, you might want to track it down,

"Under certain conditions, a business may deduct a charitable contribution as an advertising/marketing expense. For the expense to be classified as “advertising,” the business must be able to substantiate that it received a direct benefit for its donation. The cost can then be classified as an “ordinary and necessary business expense." 

According to IRS guidance, costs that can be considered advertising expenses include:

• Messages containing qualitative or comparative language, price information, or other indications of savings or value
• An endorsement
• Inducements to purchase, sell, or use the products or services"

https://blog.fabeancounters.com/bean-blog/deducting-charitable-contributions-a-guide-for-small-busin....