What is the cause of this?
did you recently make any changes to the page (to its content or URL usually) or to other stuff that could impact it, such as:
- to internal links that are pointing to this page (did you remove / overuse the anchors of those internal links?)
- to your SEO plugin that could impact noindexation / canonicalization of this page?
- to your theme (changed permalinks settings maybe)?
These can impact a page and remove it from the SERPs, so think hard about what you could have done to affect this page directly or indirectly and if you did one of these then probably that's why it vanished from the SERPs.
Oh, also... did you change hosting provider, hosting plan, or the site's theme? These could also screw your rankings too...
If you didn't do any of these it's possible that the recent google update (which seems to still be omgoing btw) had affected it, in which case I wouldn't do anything for a few more weeks (or, rather, until the update finishes) as it's possible that the page will come back on its own...
If it's not the update either I don't know in this case, I would have to look deeper into it, which I won't do obviously. But you can do it if you know what to search for
You can start by logging into your GSC and checking at which date the page disappeared and see if it's during the recent google update, or prior to that. I don't know what you should look for had the page disappeared prior to the google update, but you keep checking everything, maybe you will find a clue or something...
Also check Ahrefs / Semrush (whichever one you're using) for stuff that's happened to the SERPs / keywords / rankings / whatever else you can think of, both before, and after your page vanished. You might find something that you can pick on...