I've a website for about 10 years ... we're a team developing websites .... we've been on the first page on google for the keywords we wanted but it has been 40 days that we moved to page 2 on google search .
I'm not an expert in seo but since then we've been working on the content and our blog for about 30 days and we've made unique and very good quality of contents .
also make lots of youtube movies and worked on socials to get us back to page one
we came to page one again for about 3-4 days and again go back to page 2 . we're still losing .
there is a thing I'm suspect , we're making shopping website and now we've about 100 sites , on the footer of each site we've a back to our site , for example a website has about 5000 product pages and we've out backlink on each of them . these site are new and has no DA and rank in google .
can these backlinks damaging us ?