SEO problems - Problems with link building

I started SEO for this website from mid July 2020, my strategy plan as following:

1> Optimised On-Page SEO for all pages
2> Google Map + Social Profiles to build trust for my website
3> (06 Aug) I started using RankerX to build Tier 1 for my website (I chose EDU firstly), then use bookmarking for those links in Tier 1. I then used Speedlink as guide from RankerX to index all my backlink.

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Problems:
After started building Social Profile (on 13 August) and Backlinks (on 06 August):
1> For backlinks created by RankerX with Speedlink , many my backlinks are indexed on Google but Google Search Console and Ahrefs not recognise my backlink for more than 2 weeks.
2> Some of my SOcial Profile links has been found by Ahrefs and Google since 14 August.
3> My main keyword's position decreased (check screenshot below)
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I do not know if I made mistakes. And, Are any problem of my method for link building by using RankerX?

At this point Google has probably identified that you are getting backlinks from link farms, thousands of websites have the exact same link profile as yours, try to diversify your backlinking strategy a bit

target better links, and there was some updated during Aug 15 so possibly it’s effect too

Use quality links from high authority sites help you

Try to get links from authority site and diversify the backlink profile. Avoid low-quality links, these will harm the site performance. And also make sure that content is unique and valuable to the user.

Stop using RankerX and get guest posts / more contextual backlinks that are relevant to your site.

As the others have pointed out, Google is onto you. Try getting an authority backlink or two in order to mix things up. At this point, you’ve used up RankerX. You could add thousands more backlinks with it and nothing will change.

Low-level link building + brand new website = what you are seeing. Build better links and give it time.

For backlinks created by RankerX with Speedlink , many my backlinks are indexed on Google but Google Search Console and Ahrefs not recognise my backlink for more than 2 weeks.

Click to expand...

It takes time for the links to appear on GSC and Ahrefs, Ahrefs usually picks them up first. Just make sure they are indexed in Google and you're good

From position 12 to 15 is not a big drop. Fluctuations in SERP happens on regular basis.

You have to consider the age of your competitor website and also the backlinks profile.

How old is your website?

Try to build some high quality manual links.