Would getting guest posts save my site?

Hi! asking if i should buy backlinks or guest posts to get my site to it's normal levels of reach. provided a screenshot of my domain rating. thanks! PS: no penalties shown in GSC

It looks like your site got hit by Algo update. Algo update penalty don't show on gsc. Google silently kills the site by deranking your pages and posts.
1) find out which algo update hit you. You will need an seo expert to figure it out that is if you can't by yourself.
2) take steps recommend to you to recover from the algo penalty.
Links alone can't get your traffic back but it may help as per the recommendation.

at some point you had 252 RDs and 76k backlinks, whereas now you only have 51 RDs and 280 backlinks.

You've lost A TON of RDs and backlinks, which means that this could have caused your site to drop. This means that you've purchased backlinks, or - worse - rented them and then you've stopped paying the rent and the backlinks that got you to so much traffic (so probably good backlinks) have been taken down by the seller / leaser, and now you're suffering the consequences.

This is the first thing that comes to mind while looking at those screenshots...

The 2nd thing could be like IM Dude said: a google penalty. There's a rumour that a new google update is quietly being rolled out, and if that's true it could justify some of the recent downfalls of your rankings.

But your site's main downfall started on 21st of January, so check what's happened on / around that time in terms of google updates / changes you've made to your site or content / backlinks and / or RDs lost, etc... one of these things might have happened on, or around 20th or 21st of January and it may have triggered this penalty

I get what Im dude and tazarbm are saying, and I agree. It’s possible that a Google update hit your site, causing the rankings to drop. But honestly, I am surprised it was ranking so well with such a low number of backlinks.

Usually, without enough strong backlinks, it’s tough to maintain rankings especially when Google rolls out an update. Maybe your site benefited from low competition before, or Google was ranking it based on other factors, but the recent update might have shaken things up.

I would suggest checking what changed in the latest update and looking into a stronger backlink strategy to recover and stabilize rankings.

Buying backlinks can be risky if they’re low quality or unnatural. Guest posts on reputable sites are a safer long-term strategy.

Thanks everyone for your responses. they helped me make some progress in figuring out the issue. it seems either google is keeping me away because i got adsense banned before, or it might be because i "accidentally" installed a plugin that auto submitted my posts to gsc, spamming for over a month. another one is that google only really cares about a site's backlinks when it's active. my site used to work fine, but i shut it down for months before bringing it back 2-3 months ago. so many thoughts, but i launched a new website and bought backlinks for it a week ago, so i'll wait for some time to see what happens and figure out what the problem is. i'll keep you updated once something new occurs. again, thanks <3

You hired someone and she/he stopped the service, am right ? If yes, then he bought some monthly services like pbns and sidebar links.

As https://www.blackhatworld.com/members/tazarbm.1451019/ said, you lost so many links. Total 74k with only 250 different ips looks like a sidebar/footer for me.