Hello,
First of all, I would like to thank the moderator friends who invited me to the forum. I try to read the posts on the forum from time to time, but I haven’t been able to find time for a long time due to my busy work schedule.
I have been putting effort into an e-commerce project for a long time, but today I noticed a mistake of mine, or perhaps this situation arose when our theme was updated.
There is an H1 tag in the product name (there wasn’t before), and I also write topics in the product description sections using h1 and h2 tags. I generally try to create completely unique content, but currently, there are 2 h1 tags on the page. What do you think if I directly convert the existing 2nd h1 tags to h2? I asked this thinking that Google doesn’t like excessive changes.
The other issue is that the sector I am in is about pets; generally, 50% of the content can be the same—I mean the food ingredients, nutrition guide, analysis, etc.—so there is very little content I can change. I generally try to edit and add images myself, but due to the excess of products and lack of staff, I added many product images without editing. (Would adding a watermark be of any benefit?). I struggle to constantly enter unique content, but for example, besides these, I can write at most 5 paragraphs. There aren’t many things left to explain at length, or maybe I’m just burnt out after the 1000th product 
I look forward to your advice on these matters.
Thanks in advance.