SEMRush showing a keyword fluctuating wildly, page is a blog post that is untouched

I've got a blog post that discusses the differences between two industrial processes. Since 2019, our blog post has ranked typically between top 10 and top 20 position on Google, however last year we've suddenly begun to yoyo back and forth, reaching as high as first, and then disappearing almost entirely to 100+, what gives? I've not made any changes to this particular page in 3 years, so I'm confused why it is fluctuating so much? Literally this past week on the 28th January I was position 1, today I am position 64? While I expect minor fluctuations, especially as the page hasn't changed in 3 years, this is completely bizarre, jumping up and down all the time, and has been for around the last 12 months. Any ideas folks?